SPECIAL ISSUE ON POLITICAL VIOLENCE Research on Social Movements and Political Violence Donatella della Porta Published online: 15 July 2008 # Springer Science + Business Media, LLC 2008 Abstract Attention to extreme forms of political violence in the social sciences has been episodic, and studies of different forms of political violence have followed different approaches, with “breakdown” theories mostly used for the analysis of right-wing radicalism, social movement theories sometimes adapted to research on left-wing radical groups, and area study specialists focusing on ethnic and religious forms. Some of the studies on extreme forms of political violence that have emerged within the social movement tradition have nevertheless been able to trace processes of conflict escalation through the detailed exam- ination of historical cases. This article assesses some of the knowledge acquired in previous research approaching issues of political violence from the social movement perspective, as well as the challenges coming from new waves of debate on terrorist and counterterrorist action and discourses. In doing this, the article reviews contributions coming from research looking at violence as escalation of action repertoires within protest cycles; political opportunity and the state in escalation processes; resource mobilization and violent organizations; narratives of violence; and militant constructions of external reality. Keywords Political violence . Social movements Attention to extreme forms of political violence in the social sciences has been episodic, with some peaks in periods of high visibility of terrorist attacks, but little accumulation of results. There are several reasons for this. First, some of the research has been considered to be more oriented towards developing antiterrorist policies than to a social science understanding of the phenomenon. In fact, “many who have written about terrorism have been directly or indirectly involved in the business of counterterrorism, and their vision has been narrowed and distorted by the search for effective responses to terrorism…. [S]ocial movement scholars, with very few exceptions, have said little about terrorism” (Goodwin 2004, p. 259). Second, studies of different forms of political violence have followed different approaches, with “breakdown” theories mostly used for the analysis of right-wing radicalism, social movement theories sometimes adapted to research on left-wing radical groups, and area study specialists focusing on ethnic and religious forms. Third, and most fundamentally, there has been a tendency to reify Qual Sociol (2008) 31:221–230 DOI 10.1007/s11133-008-9109-x D. della Porta (*) Department of Political and Social Sciences, European University Institute, Badia Fiesolana, Via dei Roccettini 9, 50016 San Domenico di Fiesole Firenze, Italy e-mail: [email protected] definitions of terrorism on the basis of political actors’ decisions to use violence (Tilly 200.

1. SPECIAL ISSUE ON POLITICAL VIOLENCE
Research on Social Movements and Political Violence
Donatella della Porta
Published online: 15 July 2008
# Springer Science + Business Media, LLC 2008
Abstract Attention to extreme forms of political violence in the
social sciences has been
episodic, and studies of different forms of political violence
have followed different
approaches, with “breakdown” theories mostly used for the
analysis of right-wing radicalism,
social movement theories sometimes adapted to research on left-
wing radical groups, and
area study specialists focusing on ethnic and religious forms.
Some of the studies on extreme
forms of political violence that have emerged within the social
movement tradition have
nevertheless been able to trace processes of conflict escalation
through the detailed exam-
ination of historical cases. This article assesses some of the
knowledge acquired in previous
research approaching issues of political violence from the social
movement perspective, as
well as the challenges coming from new waves of debate on
terrorist and counterterrorist
action and discourses. In doing this, the article reviews
contributions coming from research
looking at violence as escalation of action repertoires within

2. protest cycles; political
opportunity and the state in escalation processes; resource
mobilization and violent
organizations; narratives of violence; and militant constructions
of external reality.
Keywords Political violence . Social movements
Attention to extreme forms of political violence in the social
sciences has been episodic, with
some peaks in periods of high visibility of terrorist attacks, but
little accumulation of results.
There are several reasons for this. First, some of the research
has been considered to be more
oriented towards developing antiterrorist policies than to a
social science understanding of the
phenomenon. In fact, “many who have written about terrorism
have been directly or indirectly
involved in the business of counterterrorism, and their vision
has been narrowed and distorted
by the search for effective responses to terrorism…. [S]ocial
movement scholars, with very few
exceptions, have said little about terrorism” (Goodwin 2004, p.
259). Second, studies of
different forms of political violence have followed different
approaches, with “breakdown”
theories mostly used for the analysis of right-wing radicalism,
social movement theories
sometimes adapted to research on left-wing radical groups, and
area study specialists focusing
on ethnic and religious forms. Third, and most fundamentally,
there has been a tendency to reify
Qual Sociol (2008) 31:221–230
DOI 10.1007/s11133-008-9109-x

3. D. della Porta (*)
Department of Political and Social Sciences, European
University Institute,
Badia Fiesolana, Via dei Roccettini 9, 50016 San Domenico di
Fiesole Firenze, Italy
e-mail: [email protected]
definitions of terrorism on the basis of political actors’
decisions to use violence (Tilly 2004). In
fact, there is uneasiness in using a term which is not only
politically highly contested, but also
of doubtful heuristic value. Fourth, explanations tend to focus
on either macro-level systemic
causes, meso-level organizational characteristics or micro-level
individual motivations, with
little communication between different levels of analysis (della
Porta 1995).
Some of the studies on extreme forms of political violence that
have emerged within the
social movement tradition have nevertheless been able to trace
processes of conflict escalation
through the detailed examination of historical cases. In what
follows, I briefly assess some of
the knowledge acquired in previous research as well as the
challenges coming from new waves
of debate on terrorist and counterterrorist action and discourses.
Violence as escalation of action repertoires within protest
cycles
Prior research
Social movements research places political violence in the

4. context of other forms of protest by
using Tilly’s concept of repertoires of action. A repertoire of
action describes a limited set of
forms of protest that are commonly used in a particular time and
place. Typically, the repertoire
was learned from previous waves of protest in one country, but
forms of action were also
adopted and adapted cross-nationally. The choice of action
repertoires has been considered as a
relational dynamic, developing from the interactions between
challengers and élites (Tilly 1978).
Societies occasionally experience periods of increased protest
activity involving one or more
issues and many protesting groups. These clusters of protest
activity, called protest cycles,
typically develop a sharp peak and then decline, which can be
seen when the number of
protest events is plotted over time. The repertoire of action
develops and changes during the
intense interaction within a protest cycle. The analysis of
protest cycles is particularly useful
for an understanding of the development of political violence,
as violence is frequently one of
the outcomes of a cycle of protest, though not the only nor the
most important one.
Research on such different cases as the Italian and German left-
libertarian movement
families in the late 1960s and early 1970s, or the ethno-
nationalist conflicts in Northern
Ireland and the Basque countries, showed that violence
escalated in much the same forms and
according to much the same timing, during cycles of protest that
developed in all those cases.
This was true despite the fact that the cases involved different

5. political and social actors. The
forms of action were initially disruptive because they were
unconventional, but they were
peaceful and had moderate aims, mainly claims for reform of
the existing institutions.
Although remaining mainly non-violent, the protest repertoires
radicalized at the margins,
especially during street battles with adversaries and the police
(della Porta and Tarrow 1987;
Tarrow 1989).
During cycles of protest, the development of the forms of
protest actions follows a reciprocal
process of innovation and adaptation, with each side responding
to the other. As their
adversaries adapted their tactics to counter those of the
movement, the social movements
changed their tactics in order to continue to mobilize (McAdam
1983). In the course of
experimentation with different tactics, both dissidents and
social control agents in the Italian
and German cases tested “hard” techniques, thus creating
resources for violence (della Porta
1995). The same happened in Northern Ireland and the Basque
countries, where mainly
peaceful social movements met not only state repression but
also the paramilitary activities of
death squads. This pattern also occurred to an even larger extent
in weak democracies in
Latin America (Waldmann 1993; White 1993; Wieviorka 1988).
222 Qual Sociol (2008) 31:221–230
However, after the 1970s, social movements within the left-

6. libertarian culture underwent a
learning process that primarily produced widespread support for
nonviolence. A learning
process on the part of both movement activists and the police
defused the forms of conflict that
had characterized the 1970s. In the 1980s, despite moments of
sometimes severe tension,
particularly during direct action such as the blocking of gates at
military bases, peace activists
and police were experienced in avoiding escalation into
violence (Rochon 1988, pp. 186–7).
More recently, although violence escalated in Seattle, and then
in Prague, Gothenburg and
Genoa, the large majority of activists of the global justice
movement kept violence under
control through tactical innovation: they created “violence-free
zones”; they divided marches
into blocks, according to the tactics and location; and deployed
protest marshals “armed” with
video cameras in order to ensure a stricter implementation of
nonviolent tactics (della Porta
and Reiter 2004).
New challenges
This does not mean, though, that the use of violence as a
political means has declined overall.
For social movement scholars with an interest in research on
political violence, the larger world
picture points toward the need to address types of social
movements they are not usually
familiar with, such as right-wing groups and religious
fundamentalists. As Charles Tilly (2003,
p. 58) sadly summarized, since 1945 “the world as a whole has
taken decisive, frightening
steps away from its painfully achieved segregation between

7. armies and civilian populations,
between war and peace, between international and civil war,
between lethal and non-lethal
applications of force. It has moved toward armed struggle
within existing states and towards
state-sponsored killing, deprivation, or expulsion of whole
population categories.” Clearly
more research is needed on these forms of primarily state
violence that have until now have
received little attention from social movement scholars.
Violence in context: Political opportunity and the state
Prior research
In social movement studies, repertoires for protest have
traditionally been seen as influenced
by a political opportunity structure, consisting of both a formal,
institutional aspect and an
informal, cultural one (Kriesi 1989, p. 295). A major
breakthrough in social movement
research came when researchers found that social movements
develop and succeed not
because they emerge to address new grievances, but rather
because something in the larger
political context allows existing grievances to be heard. These
contextual dimensions, called
political opportunities, include regime shifts, periods of
political instability, or changes in the
composition of elites that may provide an opening for social
movements. Conversely, a
political environment that was initially more open to social
movements may close as the state
tries to reassert control over protest, or as new groups come to
power that are more hostile to
the demands of social movements.

8. In general, research has shown that exclusive political systems
and unstable democracies
produce more radical opposition and violent escalation. Closing
political opportunities shaped
mobilization in Northern Ireland, as the inclusive and reformist
mobilizing messages of the
1960s Irish civil rights movement lost ground face to police
repression, lack of political
responsiveness, and counter-mobilizations, bringing about an
exclusivist nationalist frame in
the 1970s (Bosi 2006). Moreover, right-wing political violence
appears develop more when
Qual Sociol (2008) 31:221–230 223
political opportunities are closed off by the state than by
sustained grievances related to the
presence of migrants, or economic strains (Koopmans 2005).
Research in the new social movements (NSM) perspective has
in particular reflected on how
political and social conditions facilitate the implosion of social
actors into violence (Melucci
1982; Wieviorka 1988). In Italy as well as in the Basque
countries, the use of violence has
been interpreted as signal of a closure of the collective actors
on themselves, and their
inability to develop into a social movement or to revitalize a
social movement that has begun
to decline.
Particularly relevant in determining the evolution of
radicalization processes are the tactics

9. of policing protest and more generally the conditions under
which public order and security
are maintained (for a definition of protest policing, see della
Porta and Reiter 1998, 2004).
The development of political violence in the 1970s interacted
with paramilitary policing of
social unrest that triggered processes of radicalization among
social movements. In Italy, the
police were more prepared for “communist-led riots” than well-
organized small group violence
(Reiter 1998). Interactions on the street and other forms of
repression took particularly
dramatic forms in the Basque country between the end of
Francoist regime and the early
phases of transition to democracy. Even after transition to
democracy had been completed,
the Spanish local authorities lacked popular legitimacy in the
Basque countries. Similarly in
Northern Ireland, the traditional colonial approach taken by the
Royal Ulster Constabulary
impacted on movement strategies, as well as on the character of
organizations and the ways
in which they perceived state responses (Ellison and Smyth
2000).
Encounters between the movements and the state apparatuses
produced radicalization in a
wide variety of movement cases. The very conditions that
favored the escalation of violence in
the left-libertarian movements often stimulated radical counter-
movements as well, and thus
national “radical sectors” composed of left-wing as well as
right-wing radical groups, violent
movements and violent counter-movements. This development
was characteristic especially of
Italy, where from the very beginning of the protest cycle, the

10. student activists clashed with
neo-Fascists and, throughout the seventies, brutal conflicts
escalated among young members of
right-wing and left-wing non-underground groups who fired at
each other right in front of high
schools (della Porta 1995). Racist groups, Unionists, and
Loyalists used terror against civil
rights activists as well as ethno-nationalists in the US, Northern
Ireland and Spain, respectively.
The policing of protest derives from several characteristics of
the police forces themselves:
their military versus civil organizational structures, the police
culture, the type of training, and
the degree of professionalization and specialization. These
elements influence police strategies
as well as the police knowledge about their own role and their
own environment, affecting their
assessment of the rights of demonstrators. National structures
such as police organization,
characteristics of the judiciary, codes of laws, and
constitutional rights set constraints on protest
policing and, more broadly, institutional reactions to social
movements. But police strategies
also and even primarily depend upon political choices. They
must be studied in relation to the
changing political opportunity structure.
New challenges
A new challenge for research on the contextual opportunities for
violence arises from the global
dimensions of contemporary forms of political violence, and
from the discourse that develops
around them. In the field of political violence as well as in
social movement studies more

11. generally, research focuses on the nation-state as the central
unit of analysis. This is no longer
tenable, as both terrorism and counterterrorism go global, and
geopolitical issues as well as
wars, diasporas and the like acquire more and more explanatory
power. The effects of
224 Qual Sociol (2008) 31:221–230
radicalization linked to repression at the national level are
increasingly global ones. For instance
political repression played an important role in the
radicalization of Islamic fundamentalist
militancy, as the suppression by the Nasser regime radicalized
elements of the Muslim
Brotherhood and led individuals to transform the ideology of
modernist Islamists into a Jihadist
frame and a call to arms’ (Esposito 2002).
In line with the shift of attention to the supranational dynamics
of radicalization, there is the
need to extend the analysis to geographical areas other than the
ones traditionally addressed by
social movement studies. To date most of the cases of
radicalization studied by social
movement scholars took place in democracies. However, it is
becoming more and more
relevant to examine the dynamics of repression in non-
democratic states. Weak states with
governments that are unable to control their territory and/or
populations are particularly prone
to internal escalations, but also to the “export” of radical frames
and practices (Crenshaw 2005).
While state response and violent radicalization have

12. traditionally fed each other, greater levels
of democracy do tend to curtail violations of human rights.
State responses within
authoritarian regimes are particularly brutal (e.g. Boudreau
2004; Davenport and Armstrong
2004; Pruitt and Kim 2004; Francisco 2000; Davenport 2005).
Yet more research is also needed to address evolving repressive
strategies in democratic
regimes, as the new millennium opened with at least a partial
inversion of some trends that
had previously appeared in the police control of protest. First,
although the control of protest
was never totally taken away from private police in factories or
on campuses, the privatization
of public spaces such as shopping malls, as well as the
outsourcing of police functions to
private bodies, has increasingly challenged the state monopoly
of force. Second, if in the past
control of protest tended to be centralized at the national level,
the control of transnational
protests has brought about an increasing collaboration between
different national police
bodies, with declining transparency. This process seems more
widespread in Europe, linked
to an increasing intervention of the European Union. In this
process, not only are the rights of
social movements limited, but militarization of the police is
facilitated through tough
escalation strategies, including upgrades of police equipment,
specialized counterterrorism
training, and innovative tactics. Finally, strategies of police
control, especially but not only
at transnational counter-summits at which demonstrators from
many countries gather to
protest an international summit meeting, has often deviated

13. from the previously established
protest policing policies of negotiation and de-escalation, thus
constraining the freedom of
demonstrators (della Porta et al. 2006).
Resource mobilization and violent organizations
Prior research
The development of political violence up to the descent into the
underground cannot be
understood just in terms of environmental or macro-level
preconditions such as political
opportunities and protest policing styles. Drawing on
organizational approaches to social
movements, research in the resource mobilization perspective
has addressed the characteristics
of the organizations that went underground as well as
competition among and within
organizations within the social movement sector. At the meso-
level, organizational dynamics
play an important role. Underground organizations evolved
within and then broke away from
larger, non-violent, social movement organizations. In both
Italy and Germany in the late
1960s, the decline of the student mobilization and reduction in
available resources increased
competition among the several networks that constituted the
left-libertarian social movement
Qual Sociol (2008) 31:221–230 225
families. In Italy, the large New Left organization Potere
Operaio and Lotta Continua split on

14. the issue of violence, after having created semi-clandestine
militant subgroups. A similar
dynamic developed in Germany. In the US, the Weather
Underground developed as a fraction
of the Students for a Democratic Society (SDS) when they split
over the issue of the use of
violence, among other things, and similar dynamics were found
in Japan (Zwerman, Steinhoff
and della Porta 2000; Steinhofff 1991). Similarly, militant
nationalist movements developed
through a process of interactions, competition and coalition-
building among different streams
of Irish and Basque nationalists (Irvin 1999; Maney 2007).
Exploiting environmental
conditions conductive to militancy, these splinter groups
underwent further radicalization and
eventually created new resources and occasions for violence.
New challenges
If in this earlier context underground organizations developed
mainly into compartmentalized
hierarchical structures, contemporary extreme forms of political
violence seem instead to
follow a different model, which new technology has made
possible and new norms have
legitimized. A challenge for those studying political violence
within a social movement ap-
proach nowadays is the strongly networked structures of the
groups that are labeled as terrorist
today. While the traditional image of underground organizations
has been extremely hierar-
chical, new technologies as well as new configurations of
conflict have produced different
organizational forms (Mayntz 2004). In particular, Jihadi groups
have been said to move from

15. a hierarchical organizational model towards a more horizontal
model.
Culture, frames, and narratives of violence
Prior research
Political violence is mainly symbolic: the cultural and
emotional effects that it produces are
more important than the material damage. Social movement
research has stressed the role of
cultural processes in the development of political violence,
looking both inside and outside
radical organizations. Governmental policies and politics are
influenced by the symbolic
struggles that evolved, in different public arenas, between a
“law-and-order” and a “civil
rights” coalition (della Porta 1996). In Italy and Germany as
well as in Northern Ireland and
the Basque Country in the 1970s, different political and social
actors coalesced to form two
opposing coalitions: a law and order coalition asking for tough
measures against protestors,
and a civil rights coalition asking for more democracy. Both
used the media to address and
sway public opinion about legitimate forms of protest and
acceptable forms of policing, thus
ultimately affecting both movement and state strategies.
Generally, the emergence of protest
increased public concern for law and order, prompting the more
conservative elites to choose
hard-line tactics, but, at the same time, demands for a more
liberal understanding of citizen
rights also spread in the society. The development of political
violence then may be seen as a
force that polarizes the debate on democratization, often

16. resulting in a weakening of the civil
rights coalition.
The ideas that different groups use to characterize their
positions and justify their actions
are often analyzed by social movements scholars as “frames”
that define the problem, identify
protagonists and antagonists, and point to particular lines of
action. Various frames may be
constructed by both elites and social movements, in order to
mobilize support for their chosen
course of action. They derive their explanatory consistency and
emotional power through
226 Qual Sociol (2008) 31:221–230
narratives or stories that connect the group’s collective past to
their present situation. The
clash of these cultural frames is an important aspect of the
analysis of how violence escalates.
In cases where a consolidated democracy was absent, the frames
that political elites used to
define the “dangers” of protest, and that activists used to define
their rights harkened back to
“older” national traditions and conflicts. When the student
movements emerged in the 1960s,
the governing elites of the young Italian and German
democracies felt particularly endangered.
In Germany, recollections of the end of the Weimar Republic
were often quoted in the press,
and the students’ “breaking of the rules” was compared to the
political violence that preceded
the rise of Nazism. In Italy, the state justified its repression of

17. the student movement by
appealing to “anti-fascist” sentiments. A similar dynamic was at
play in the Japanese case
(Zwerman et al. 2000).
Cultural effects have also been analyzed within social
movement organizations themselves.
Feeling excluded from the political system, social movements in
these same historical cases
escalated their demands, with both the elaboration of radical
frames of meaning and a
revolutionary rhetoric, and the development of a meta-conflict
about the very nature of
democracy. The evolution of the conflict from the social to the
political sphere offered
social movements the possibility of building larger alliances.
However it also threatened
their adversaries, who read the demands for expanded
democracy as attacks against
“democracy” itself. The hard-liners therefore gained momentum
and pushed for a style of
policing that increasingly alienated the activists from the state
(della Porta 1995).
The Italian activists claimed they had to carry on their fathers’
Partisan movement against a
“fascist state,” a movement that according to them the Old Left
had abandoned. The German
activists asserted that they had to resist with all means the new
“Nazi” state to avoid repeating
their fathers’ mistakes and redeem their shame. In Ireland and
the Basque countries, the ethno-
nationalists resorted to the long-standing narrative of
oppression of minorities: the Catholic
religious minority in Ireland or the ethnic Basque people in
Spain. The transition agreement

18. was not sufficient to legitimize a Spanish State in the Basque
country, which accused it of
following the Fascist tradition established during the long-
lasting Francoist regime of resorting
to torture against Basque patriots. Similar memories of colonial
rule fed the conflict in
Northern Ireland.
Specific narratives are used to legitimize violent action during
the process of organizational
competition within social movements as well as within the
overall protest cycle. In Northern
Ireland as well as in the Basque countries the narrative of
previous waves of armed insurrection
against the English and Spanish occupants re-emerged in the
1970s. Nationalist narratives are
also used to justify other forms of nationalist violence, being
“certified” by powerful actors
(Demetrious 2007). Violent organizations of the extreme right
motivate individuals to action
through discourses that provide followers and potential
followers with rationales for parti-
cipating in their organization (Bjorgo 2004). In the rhetoric of
the extreme right, the super-
iority of one race, religion, gender, or sexual orientation over
others (O’Boyle 2002 p. 28),
religious fundamentalism, or ‘blood’ and ‘honor,’ are some
main justifications of violence
(della Porta and Wagemann 2005).
This does not mean that political violence derives directly from
the presence of ideologies
that justify violence (Snow and Byrd 2007). In Italy and
Germany, radical ideologies
engendered radical violent repertoires only when political
opportunities triggered escalation

19. (della Porta 1995). In Ireland, as mentioned earlier, changing
political opportunities affected
the shift from a civil-rights to an ethno-nationalist discourse
(Bosi 2006). For this reason,
social movement research focuses less on very broad ideologies
and more on the specific
frames and narratives that arise in a particular situation, and
how changing political
opportunities affect their appeal.
Qual Sociol (2008) 31:221–230 227
New challenges
The research on recent waves of political violence can build
upon this knowledge, addressing
some emerging narratives. While in the past the discourses were
more classically political (left–
right or even ethno-nationalist), and therefore easier to address
within the traditional categories
of research on social movements, nowadays the use of the
“clash of civilizations” metaphors
used in different forms by different actors require some new
reflections. Various religious
narratives have been used to justify violence (Juergensmeyer
2000). With reference to religious
fundamentalism and its radicalization, it has been remarked that
culture provides a “tool kit”
of concepts, myths, and symbols from which militant
organizations could selectively draw to
construct strategies of action (Hafez 2003). Although
differences in religions per se are hardly
a genuine source of political conflict, their content can shape
conflict behavior in the direction

20. of either escalation or de-escalation of violence (Hasenclever
and Rittberger 2000).
Micro-dynamics: Militant constructions of external reality
Prior research
Research has demonstrated that organized violence and the
groups that specialized in violent
repertoires developed gradually. It was during the fights with
right-wing radicals and/or the
police that a number of radical organizations such as Lotta
continua in Italy and the “blues” in
Germany constructed semi-clandestine structures, established
specifically to plan and carry out
violent actions. The research within the tradition of symbolic
interaction, later revisited within
the cultural turn in social movement studies (Johnston and
Klandermans 1995; Jaspers et al.
2001), has helped to single out some micro-dynamics of
escalation, focusing especially on
the ways social movement activists perceive and construct their
social reality.
State repression as well as internal competition affected social
movement activists through
cognitive, affective and relational mechanisms. First, state
“repression” created martyrs and
myths: for example, the killing of Benno Ohnesorg by police
during a protest against the shah
of Iran’s visit to Berlin; or Bloody Sunday in Northern Ireland;
or the “battle” with the police
in Valle Giulia in Rome, which took on a legendary quality for
Italian activists. Police actions
of this sort delegitimized the state in the eyes of the activists by
creating “injustice frames”

21. (Gamson et al. 1982). Moreover, state repression encouraged
secondary deviance, the
individual’s even stronger commitment to his or her deviant
behavior—which brought about
a radicalization both of people who are directly hit by
repression, but also the activation and
radicalization of supporters. Cognitive, affective and relational
mechanisms accompanied the
activists’ descent into the underground, but parallel mechanisms
also affected de-
radicalization (della Porta forthcoming).
New challenges
Reflection on this dimension in the social movement tradition is
certainly helpful for future
research, but new waves of political violence nevertheless bring
some challenges to the ways
in which processes of individual radicalization have been
addressed. Research should
address, in particular, individual paths of protest escalation in
non-democratic countries as
well as in development of religious types of commitments—
fields that are rarely analyzed
within a social movement perspective. Additionally, while past
research focused on “vicious
circles” of radicalization, empirical analysis is needed on the
contributions of social
228 Qual Sociol (2008) 31:221–230
movement activists to processes of de-radicalization and
mobilization of groups in civil
society such as unions and local organizations in pushing

22. political parties to find peaceful
solutions.
In conclusion, even though social movement attention to
political violence has been
discontinuous, there are nevertheless some interesting
contributions that could help shed light
on emerging waves of political violence. At the same time,
however, more reflection is needed
in order to adapt existing tools to address some new
characteristics of recent processes of
radicalization, and for the filling of gaps in the social science
literature.
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Donatella della Porta is Professor of Sociology in the
Department of Political and Social Sciences at the
European University Institute. Among her recent publications
are Le Ragioni del No (with Gianni Piazza),
Feltrinelli 2008; The Global Justice Movement, Paradigm, 2007;
(with Massimiliano Andretta, Lorenzo
Mosca and Herbert Reiter), Globalization from Below, The
University of Minnesota Press, 2006; (with Abby
Peterson and Herbert Reiter), The Policing Transnational
Protest, Ashgate 2006; (with Mario Diani), Social
Movements: An Introduction, 2nd edition, Blackwell, 2006;
(with Sidney Tarrow), Transnational Protest and
Global Activism, Rowman and Littlefield, 2005.
230 Qual Sociol (2008) 31:221–230
Research on Social Movements and Political
ViolenceAbstractViolence as escalation of action repertoires
within protest cyclesPrior researchNew challengesViolence in
context: Political opportunity and the statePrior researchNew

28. challengesResource mobilization and violent organizationsPrior
researchNew challengesCulture, frames, and narratives of
violencePrior researchNew challengesMicro-dynamics: Militant
constructions of external realityPrior researchNew
challengesReferences
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