While there is increased attention to child marriage, defined as marriage before 18 years of age, in countries where the practice is especially prevalent, less attention has been directed at understanding the factors affecting relationships, marriage and cohabitation among adolescents affected by conflict and displacement. This article presents factors which contribute to early relationships and informal marriages in conflict and post-conflict settings, based on qualitative research undertaken among two distinct populations in Uganda: internally displaced persons in Mucwini transit camp in northern Uganda and Congolese refugees in the Nakivale refugee settlement in southwestern Uganda. Themes were examined through a social–ecological framework. Findings indicate that fundamental shifts in economies, family relationships, and communication combined with structural changes encountered in settlements resulted in changed relationships and marriage patterns. Participants reported that poverty, splintering of family, and lack of education – which they believed to be exacerbated by conflict in both settings – had profoundly affected the views, perceptions and behaviours of youth around relationships and marriage. We identify interventions applicable to humanitarian settings that would offer refugee and internally displaced adolescents greater and more meaningful opportunities for development.