In this paper we study the political participation of ex-combatants and its consequences on the electoral landscape. Although the relationship between elections and conflict has been studied extensively, in this paper we focus on the reasons why ex-combatants participate in democratic politics and the way in which they do so. We use individual information on the participation in communal assemblies’ meetings of more than 10,000 former members of the paramilitaries in Colombia and data on the universe of candidates who stood for election between 2003 and 2015. On the one hand, we describe the characteristics of this participation: we analyze who participates in politics, where they do it, and what kind of activities they carry out. On the other hand, we study the impact of their participation on the selection and performance of candidates. Relying on a difference-in-difference strategy, we explore the impact of the participation of former ex-combatants on right-wing candidates, polarization, and the competitiveness of elections. The paper allows us to advance our understanding of electoral dynamics in the post-conflict period, making use of detailed information on participation and wartime experience.