One of the core problems of peacebuilding conducted amidst violence is the complex relationship between the security and development arenas, two major pillars in peacebuilding that international peacebuilding frameworks consider to be inextricably linked. Yet, empirical research on how violent environments influence how peacebuilding policies in those two arenas relate to each other on the ground is scarce. This paper explores the relationship between security and development in peacebuilding policies in Colombia, a country barely emerging from decades of protracted armed conflict that continues to experience high levels and of violence. It particularly focuses on Colombia’s efforts to substitute crops used for illegal purposes with alternative forms of sustainable livelihood in order to curb what is perceived as one of the biggest threats to both security and development in the country. Through in-depth interviews with multiple actors involved in this effort, ranging from state and regional institutions and members of the army and the police force to different actor groups at the local community level, the paper explores how Colombia's violent environment shaped the country's efforts to deal with the substitution of drugs used for illegal purposes. The findings argue that continued violencecreates considerable obstacles for local peacebuilding actors trying to follow the international policy imperative to implement peacebuilding strategies that intend to pursue security and development at the same time. Violent peacebuilding environments can significantly counteract and undermine the successful outcomes of peacebuilding, turning security and development programs against each other and blocking each other's success.