Why were El Salvador's FMLN and Peru's Shining Path able to mount such serious revolutionary challenges in the 1980s and early 1990s? And why were they able to do so despite the fact that their countries' elected governments were widely considered democratic? These two guerrilla groups were very different, but both came close to success. To explain why, the author examines the complex interplay among political and economic factors, the nature of the revolutionary organization, and international actors.