In cities facing housing shortages, vulnerable newcomers almost always live with family or friends upon arrival. While social networks are often seen as a source of support that facilitates migration and settlement, research has also shown that newcomers can be exploited by established migrants and relatives. Challenging the dichotomy between positive and negative social capital, this article reveals how exploitation and support coexist within social relationships. It shows how exploitation emerges from the ambiguous and implicit obligations of reciprocity that is inherent in informal support. Examining the informal housing arrangements and experiences of Colombian newcomers in Rotterdam (NL), this article analyses what support they receive from their hosts and how they reciprocate. It shows how the arrangements are shaped by the unequal positions of guests and hosts, and how they involve relational work. Through negotiating informal housing arrangements and reciprocity, guests and hosts negotiate and shape their relationship. The article draws on anthropological theories of gift-giving to explore the tensions and uncertainties that characterise hospitality. It shows how attention to reciprocity makes it possible to move beyond the opposition between support and exploitation and to understand how relationships can simultaneously be both supportive and exploitative.