In transitions from armed conflict, human rights defenders play an important role: in many cases, they are the local protagonists of the peace process. At the same time, they are at high risk of becoming victims of post-war violence. This article explores how states can protect defenders from such violence by presenting a case study of the Colombian transition, which has been characterized by high rates of homicides of defenders and threats against their physical integrity. Based on qualitative interviews with experts involved in protection, the article argues that violence against defenders may evolve into a systemic problem in post-conflict settings. In such contexts, protection must go beyond providing individual security measures to defenders at risk. Instead, it should follow a collective approach that emphasizes the security of communities and organizations, strengthens their capacities and relations with the state, and strives to dismantle the armed groups responsible for attacking defenders.