Decades of development history show that rural agricultural policies and government support for specific en vogue crops can seriously alter land rights, land tenure regimes and land use strategies for local people in tropical forests. Today, oil palm is such a crop, and it is an emergent commodity that is proliferating in the Peruvian Amazon. This paper asks: How is government interest in promoting oil palm development affecting property rights formalization for smallholders in the Peruvian Amazon region of Ucayali, and what are the socio-ecological implications? While there are strong theoretical reasons that expect these phenomena to be related, the precise nature of their interaction has not been rigorously examined in Peru. The study analyses data from a large household survey, and three years of participant observation work in those villages to unpack how these factors interact. The paper presents descriptive results comparing smallholder claims to their formal rights, and finds a large discrepancy between de facto and de jure land ownership scenarios – especially with relation to old-growth forest fragments. Furthermore, whilst our statistical model testing qualifies our hypothesis about the link between oil palm and land right in the region at both the household and village levels, it is not a direct causal relationship. The empirical results suggest a more complex nuanced picture of how migration, oil palm expansion and development are more broadly linked to land use change in the region. We conclude with policy recommendations that could facilitate improved forest conservation in the area, and a more equitable distribution of land rights to smallholders.