How do dictators coup-proof their armed forces from within the barracks? Coup-proofing is an important aspect of autocratic survival, but execution can be challenging due to the secrecy of plots and the vast size of the armed forces. Counterbalanced state security forces are more effective at resisting coups, but less effective at noticing signs of plots before they can be launched. If dictators wish to prevent coup attempts from occurring in the first place, they may decide to recruit and commission cadres of loyalists directly into the armed forces as political officers, tasked with monitoring for and reporting signs of disloyalty within the ranks. This article explores the development and use of these political officers within dictatorships, arguing that they are especially effective at preventing coup attempts. It also makes the case that their institutional design, while effective at detecting coup plots, makes them less useful at resisting coups that have reached the execution phase. I test these arguments on a cross-national sample of dictatorships from 1950 to 2010, finding strong evidence that political officers are incredibly effective coup detectors, but not coup resisters. These findings have important implications, particularly as several resilient modern dictatorships continue to rule with well-developed political officer systems.