A key component of peace processes and post-conflict reconstruction is the disarmament, demobilization, and reintegration (DDR) of ex-combatants. I argue that DDR programs imply multiple transitions: from the combatants who lay down their weapons, to the governments that seek an end to armed conflict, to the communities that receive—or reject—these demobilized fighters. At each level, these transitions imply a complex equation between the demands of peace and the clamor for justice. However, traditional approaches to DDR have focused on military and security objectives, which have resulted in these programs being developed in relative isolation from the field of transitional justice and its concerns with historical clarification, justice, reparations, and reconciliation. Drawing upon my research with former combatants in Colombia, I argue that successful reintegration not only requires fusing the processes and goals of DDR programs with transitional justice measures, but that both DDR and transitional justice require a gendered analysis that includes an examination of the salient links between weapons, masculinities, and violence. Constructing certain forms of masculinity is not incidental to militarism: rather, it is essential to its maintenance. What might it mean to “add gender” to DDR and transitional justice processes if one defined gender to include men and masculinities, thus making these forms of identity visible and a focus of research and intervention? I explore how one might “add gender” to the DDR program in Colombia as one step toward successful reintegration, peace-building, and sustainable social change.