In recent years, social scientific research on nonviolent resistance has burgeoned. Yet many studies focus on the factors associated with nonviolent movements' success or failure. In her book, Wendy Pearlman poses different questions. Instead of asking when and how nonviolence works, she asks why some activists choose nonviolent tactics while others choose violent ones. Additionally, she asks why movements may, over time, shift between armed and unarmed strategies.

To address these questions, Pearlman analyzes the Palestinian national movement from 1918 to the second intifada of 2000. She draws upon a multiplicity of sources including archival material, statistical data compiled by various research institutes, investigative reports conducted by nongovernmental organizations, memoirs of those involved in the nationalist struggle, fieldwork, and interviews with 48 Palestinian resisters. She uses this data to engage in “process tracing”—an analytic method that enables her to identify causal factors that led movement participants to adopt armed or unarmed tactics.

To explain the Palestinian movement's tactical choices and shifts, Pearlman develops the “organizational mediation theory of protest.” This theory holds that nonviolent resistance requires discipline, clear strategic direction, and coordination—something only unified movements can provide. Specifically, she argues that “while the paths to violence are multiple, there is only one prevailing path to nonviolent protest: a path that requires a movement to have or create internal cohesion” (p. 2). Why is cohesion so important to nonviolent resistance? Pearlman notes that cohesion is essential for mass mobilization. While terrorist groups can carry out campaigns with only a few individuals, large numbers of participants are necessary for successful boycotts and strikes. Additionally, cohesion is needed to maintain nonviolent discipline. Unity also improves a movement's ability to construct and implement an effective strategy. Conversely, internal fragmentation means that a movement's ability to constrain aggression is weakened and that subgroups often emerge with a more militant agenda that they pursue through more militant methods.

To demonstrate how cohesion and fragmentation shape movements' tactical choices, Pearlman guides the reader through five historical stages of the Palestinian struggle: British control (1918–48); the emergence of the Palestine Liberation Organization (1940–87); the first intifada (1967–93); the Oslo peace process (1993–2000); and the second intifada (2000). She measures cohesion by the degree of unified leadership, the strength of the movement's institutions, and the extent of activists' collective purpose and goals. On this basis, she argues that cohesion always preceded nonviolent struggles, whereas fragmentation consistently led the movement toward a violent path. Although the author acknowledges that other factors affect tactical choices—such as strategic calculations and access to material resources and targets—she makes a persuasive case that cohesion/fragmentation had a powerful influence in the Palestinian struggle. To demonstrate the utility of her organizational mediation theory of protest beyond this single case, she devotes a separate chapter to the occurrence of these patterns in Northern Ireland's self-determination movement and South Africa's anti-apartheid struggle.

In terms of contributions, Pearlman argues that her study offers several insights. First, her organizational mediation theory expands our knowledge about the factors shaping tactical choices. Within the field of social movements, structural models emphasize how tactical shifts are instigated by macro-level changes, such as the decline of a movement cycle or escalating state repression. Other movement researchers emphasize cultural factors, arguing that tactical choices reflect ideological commitments or personal preference. Still others maintain that strategic calculations are the driving force behind tactical choices. Pearlman offers an alternative perspective by arguing that organizational traits have a strong influence on whether a movement is even capable of undertaking nonviolent forms of resistance. Second, she makes another contribution by challenging the scholarly tendency to view movements as unified entities. Third, she offers us a nuanced view of conflict, revealing that intense conflicts that generate high levels of anger do not automatically lead to violence, just as lower-intensity conflicts do not guarantee nonviolent forms of action. Fourth, the author states that she is bridging different literatures and facilitating dialogue among researchers within the fields of social movements, security studies, conflict resolution, and civil resistance studies.

Indeed, this may be one of the most valuable contributions of all. Political scientists have traditionally studied armed conflict, while social movements researchers and civil resistance scholars have studied unarmed conflict. Yet, as Pearlman notes, these forms of resistance may occur simultaneously within the same struggle. Moreover, one movement may shift from one method to the other. Thus, it makes little sense to study them in isolation, and Violence, Nonviolence, and the Palestinian National Movement will undoubtedly help promote interdisciplinary dialogue and theoretical cross-fertilization.

In addition to the contributions identified, I would like to underscore a couple more. Pearlman provides numerous insights into the role and influence of movement leadership. Perplexingly, movement scholars have paid relatively little attention to leadership issues, preferring to emphasize the significance of structural factors, historical processes, and strategic mass mobilization. Yet leaders can play pivotal roles, and the author carefully analyzes a plurality of leadership styles as well as their consequences. For instance, she discusses how Palestinian leader Yasir Arafat cultivated a “fatherly benefactor” mystique that evoked personal loyalty among activists and helped the movement overcome its internal points of dissension. Yet this also created a long-term problem when Arafat died and his successor, who did not possess such charisma, was left to find other means of unifying the movement. If movement scholars have any doubts about the value of studying leadership, Pearlman makes a compelling case for its significance—particularly in building internal cohesion.

Another valuable contribution is the author's discussion of methods for managing movement fragmentation. Not only does she document the strategies that various Palestinian groups used but she also evaluates their long-term effects. For example, she shows how the Palestine Liberation Organization's consensus decision-making process was implemented to mend internal rifts. Yet the result was that movement goals reflected the lowest common denominator of diverse Palestinian groups. It also gave minority voices undue influence as they could essentially use veto power. Arafat sometimes used another strategy for managing fragmentation: the neopatrimonial distribution of benefits, goods, and services. While this sometimes worked on a temporary basis, it created new problems of corruption. Therefore, strategies that work in the short run can generate other challenges in the long run.

Obviously, there is much to admire about this book. It is clearly written, cogently argued, and full of interesting insights. Compared to the valuable contributions made by this book, my critiques should be viewed as quiet quibbles. Nonetheless, there are several points I would like to raise. First, I wonder how generalizable the organizational mediation theory is to other types of movements. Pearlman makes a case that it is difficult, indeed virtually impossible, for a movement to use nonviolent tactics in the absence of strong leadership and authoritative institutions. Yet the US women's movement arguably has neither (see, for example, Jo Reger's “Where Are the Leaders? Music, Culture, and Contemporary Feminsim,” American Behavioral Scientist 50 [June 2007]:1350–69) and has engaged in nonviolent direct action for decades. In fact, many contemporary Western activist groups eschew centralized leadership and formal movement organizations, favoring locally initiated acts mobilized by a radically democratic and egalitarian set of actors. Hence, it seems likely that Pearlman's theory is mostly relevant to self-determination movements in high-intensity conflict settings.

I had also hoped to see more theorizing about cohesion. Of the three measures of cohesion—unified leadership, authoritative institutions, and a strong collective purpose—which matters most? Are they all equally important? Must all three be present in order for a movement to successfully adopt nonviolence? Or can strong leadership overcome weak institutions to mobilize the masses in civil resistance campaigns? And how much cohesion is needed? Since no movement has complete unity, where is the threshold whereby there is sufficient cohesion to enact nonviolent resistance? I have no doubts that cohesion matters. In fact, this finding is consistent with my own research in Nonviolent Revolutions: Civil Resistance in the Late 20th Century: I found that internally divided movements did, indeed, have trouble attaining their goals. Yet in my study, and my earlier research on the international Plowshares movement (Religion and War Resistance in the Plowshares Movement, 2008), I found that groups could indeed use nonviolent forms of resistance without strong leadership or authoritative institutions. It was difficult for them to sustain this resistance or achieve victory, but they could experiment with nonviolence and launch small-scale campaigns of civil disobedience. Thus, it raises a question for me: Is cohesion really necessary for the adoption of nonviolence? Or is some (unspecified) level of cohesion necessary for launching larger-scale campaigns, such as strikes and boycotts, and sustaining this form of struggle over time?

I also wish that Pearlman had further developed her analysis on fragmentation. She delineates numerous sources of fragmentation, distinguishing between those that come from within and those generated as a result of external forces. Yet which have the most detrimental effects on movements? Does external intervention cause more problems than internal conflict between movement rivals? Do ideological differences among resisters pose more challenges to a movement than a series of setbacks in the face of an intransigent opponent?

If Pearlman had explored these questions, further developing her analysis on cohesion and fragmentation, her theory of organizational mediation would have been more nuanced and robust. Nonetheless, this book charts new territory for other researchers to explore. It will undoubtedly stimulate a new set of inquiries and debates about the reasons why groups adopt nonviolence.