Why do some small terrorist and guerrilla groups succeed in becoming full-blown insurgencies while many others fail? Proto-insurgencies face many difficulties in creating an insurgent movement: they must create a politically salient identity, harness a compelling cause, create an effective sanctuary, and defeat both violent and peaceful organizational rivals, all while evading the police and security services of the much more powerful state. Outside support is a mixed blessing for proto-insurgents. Often, the ultimate success of the proto-insurgency in becoming a full-blown insurgency depends on the mistakes of the government it opposes.