Military integration seeks to improve counterinsurgency and peacebuilding outcomes by incorporating former rebels into preexisting or new state security forces during or after civil wars. While peacebuilders continue to promote military integration, there is mixed evidence about its effectiveness and the mechanisms through which it affects counterinsurgency and peace duration. One underexplored mechanism is the effect of military integration on intelligence capacity and the information available to security forces. Information is key to successful counterinsurgency and peacebuilding efforts, and I argue that military integration of ex-rebels can improve intelligence capacity by providing gains in knowledge of human and physical geography, access to preexisting social networks and informants, and knowledge of the relative effectiveness of government and rebel tactics. I illustrate these improvements with evidence from conflicts across time and space and brief case narratives from the Philippines, Uganda, and Rwanda. I conclude by discussing policy implications, cases of unsuccessful integration and negative effects on intelligence, and questions for future research on the intelligence aspect of military integration.