This research is concerned with how in/security is understood and the implications of contested meanings of in/security. The basic premise of this thesis is that in/security in itself has no meaning and thus cannot exist in isolation. Instead, in/security is always defined in relation to something or someone. How we understand in/security derives from the contexts we navigate and the identities we construct. An inquiry into in/security therefore demands incorporating a multiplicity of narratives and discussing these in relation to each other. While scholars have called for a greater emphasis on exploring in/security in marginal sites, I argue that accounts from the margins must not be at the exclusion of other more dominant narratives. Such analysis â placing the elite/margin, included/excluded, powerful/weak â in the same framework in order to produce a relational account of in/security is largely missing. This thesis sets out to provide a rich and detailed understanding of the everyday complexities of in/security. I propose a framework for capturing relational and contextual dimensions of in/security, and the implication of contested meanings of in/security understandings. Through an in-depth case study in the context of the transitions towards a post-conflict period in Colombia, following five decades of armed conflict, I inquired into in/security understandings at the margins in relation to the centre. The margins were represented by conflict-affected communities whereas the centre was represented by the Colombian government and key security sector institutions. The research found several relational dimensions of in/security understandings between the state- and the marginalized community-levels. Moreover, contextual and identity factors had a significant impact on how in/security was spoken about and what was spoken of. Through the framework, it was possible to see in continuum the way deeply ingrained understandings of in/security reproduce violence as the government seeks to transition the country into a post-conflict period following five decades of armed conflict. The research, through a detailed empirical case study, supports the view that in/security is relational and derivative of context and with ties to identity. It contributes to further our understandings of in/security at three distinct levels. At the theoretical level, the research builds upon existing literature in the field of security studies to advance an enhanced understanding of the relational and contextual dimensions of in/security, the contested meanings of in/security and the implications thereof. Methodologically, it proposes an alternative framework to capture the relational dimensions through shifting the problem formulation from a traditional focus on who is to be secured from what threats to how in/security is understood by different people/communities in different contexts. Empirically, it contributes to an off-centred understanding of in/security dynamics in the official transitions into the post-conflict period in Colombia. Through its empirical evidence it has the potential to offer an important contribution to the analysis of post-conflict transitions more generally.