This paper critically engages with the implications of the “affect turn” in the geographies of development and volunteering. By way of considering “affective life” at a residential youth care centre in Peru through an ethnographic study, we aim to contribute to current discussions of “(self‐)transformation” taking place through affectivity in the experience of volunteering. Conceptually, our approach to investigating “affective life” and volunteering involves two steps. First, we critically review this body of work's recent focus on the individualistic mode of volunteer self‐transformation in encountering “vulnerable others.” We identify the need to think about affect and embodiment also from the perspectives of the “vulnerable” groups whose lives are entangled with the presence of international volunteering. Second, we argue for an affect‐informed approach to socio‐politically shaped vulnerability, with a particular emphasis on lived experiences and affective capacities related to enduring social and material conditions. Against the backdrop of marginalisation of adolescent mothers from rural and indigenous backgrounds, many of whom are survivors of sexual abuse, we analyse the experiences of these youths living at a specific residential care centre and interacting with volunteers on a daily basis. In doing so, we employ a series of perspectives from the residents, while taking into account the organisational environment. We also show the complex ways in which resident–volunteer encounters are at play in life‐enhancing affective states, capacities, and relations emerging among the residents. Our findings on the residents' self‐ and shared capacity of transformation highlights the importance of attending to the spatialities of affective life in academic work focused on the contemporary geographies of international volunteering.