Over at the Monkey Cage, John Sides runs through the evidence on why individuals join militias during civil wars. "[P]articipation in a military faction does depend on an individual’s relative social and economic position, the costs and benefits of joining, and the social pressures that emanate from friends and community members." Moreover, the "pressure" isn't so much in the category of eloquent and friendly persuasion, as threats that make participation something less than a voluntary activity. I was going to snarkily analogize this to Facebook, but that's probably not appropriate here. On a more optimistic note, Sides also links to some interesting papers (here and here) on how to demilitarize and reintegrate civil war participants.
