Can targeted land reform reduce levels of civil war conflict by mitigating the factors that contribute to rural rebellion? This paper uses new micro-level data on land reform and insurgency at the municipal level from Colombia from 1960-2000, a country with high rates of land inequality and informal land ownership, to test whether land reform undercut subsequent guerrilla activity. The reform had two distinct aspects. Politically powerful large landholders blocked most large-scale reform, which resulted primarily in an enduring, low-intensity and geographically dispersed reform that spurred low levels of insurgent activity. Larger-scale reforms were only implemented in areas that threatened serious violence and had the potential to harm elite interests, and in these limited areas reform reduced guerrilla activity. This suggests that while land reform can be an effective counterinsurgency policy, it may be politically difficult to implement at a sufficient scale because it threatens the status quo. Replication Data Information: Data are aggregated to municipal divisions from the year 1985 based on the Colombian Census Bureau's (DANE) list of political divisions (DIVIPOLA).