This paper offers important insights into the contemporary nature of youth transitions and the ways in which religious affiliation and engagement with international volunteering influences and interplays with negotiations of the life course. Situated within interdisciplinary debates about youth transitions, as well as discussions about relational geographies of age, religion and voluntarism, we demonstrate the multiple relationalities that are at play as young religious international volunteers negotiate the transition to religious adulthood. We focus on religious, vocational and aged relationalities to explore how these are engaged with, and experienced by, young people 'over there' in Latin America and 'back home' in the UK. Additionally, we explore how these relationalities shape identities within and between religiosity, age (youth) and volunteering, and how these are (re)organised through networks, flows and mobilities. To do so, we draw on our analysis of the experiences of young volunteers who participated in faith-based international volunteering with an evangelical Christian organisation that sends teams of young people on short-term missions to Latin America. We draw on our analyses of two sets of interviews with 22 young volunteers, 14 of whom also completed a diary about their experiences, supplemented by four focus groups. Our analysis points to the ways in which the spatial emphasis of geographical engagements with youth transitions can be well informed through considerations of religion; a key challenge being how young volunteers renegotiate their sense of religious self on returning 'back home'. In addition, although our participants displayed some self-reflexivity about the social construction of age, they did not necessarily exhibit an understanding of the power underpinning their encounters with others. Finally, our findings open up possibilities for appreciating the diversity of volunteering experiences and the role that volunteer organisations have in shaping the expectations and aspirations of those who participate in their programmes.