"Implicit in recent scholarly debates about the efficacy of methods of warfare is the assumption that the most effective means of waging political struggle entails violence. Among political scientists, the prevailing view is that opposition movements select violent methods because such means are more effective than nonviolent strategies at achieving policy goals. Despite these assumptions, from 2000 to 2006 organized civilian populations successfully employed nonviolent methods including boycotts, strikes, protests, and organized noncooperation to challenge entrenched power and exact political concessions in Serbia (2000), Madagascar (2002), Georgia (2003) and Ukraine (2004–05), Lebanon (2005), and Nepal (2006). The success of these nonviolent campaigns—especially in light of the enduring violent insurgencies occurring in some of the same countries—begs systematic investigation."
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"This study aims to fill this gap by systematically exploring the strategic effectiveness of violent and nonviolent campaigns in conflicts between nonstate and state actors using aggregate data on major nonviolent and violent resistance campaigns from 1900 to 2006."
"Why Civil Resistance Works: The Strategic Logic of Nonviolent Conflict" by Maria J. Stephan and Erica Chenoweth, International Security, Vol. 33, No. 1 (Summer 2008), pp. 7–44. (Online here: http://belfercenter.ksg.harvard.edu/f...

Erica Chenoweth's website here: http://www.ericachenoweth.com/researc...