What are the implications of donor agencies pursuing contradictory approaches in the same locale? The question is interesting for two reasons. The first is that, while critical case studies of individual interventions are common, "donor collision" is not widely reported. The phenomenon poses an alternative explanation for the failure of donor interventions that challenges universalist assertions by both modernists and post-developmentalists. The second reason is that the future of Overseas Development Assistance (ODA) and the interventions of a Global North-dominated donor infrastructure in the Global South are once more topical. Recent contributions have debated the implications of current trends for ODA and its associated policies and practices, collectively defined by Gillian Hart as "big D" (Hart, 2001). Such trends include rising middle classes in the Global South and economic convergence with the North, a "universal" set of Sustainable Development Goals and the now looming challenge of a changing climate. The global problem of contested rights in "agrarian environments" is of particular relevance to these debates. The need to protect the "lungs of the earth" was assuming a higher profile due to the rising urgency of changing climate before the Covid-19 pandemic. With future pandemic risk associated with land use change in biodiversity hotspots, a global focus on conservation and biodiversity is likely to sharpen. The question of how to reconcile conservation outcomes with the land rights of forest dwelling populations is, therefore, of general and increasingly urgent importance. The study is set in an agrarian environment in Bangladesh, where for twenty years different donor agencies have pursued contradictory approaches to this general and urgent question. On the one hand, USAID has supported Forest Department interventions, which are broadly exclusionary and are predicated on the negation of the local Indigenous Peoples' land rights. On the other, various agencies have supported such rights, explicitly challenging Forest Department authority over the area. Through analysing why and how donors collide in this instance, the study sets out a number implications for general development theory and practice. The three most important are that, first, more work is required on inter-donor conflict as a cause of development failure. Second, the future of big D will continue to be dominated by very old questions of politics, participation and institutions. Finally, blanket endorsement of "national partnership," particularly in more authoritarian contexts, is likely to result in significant human and environmental costs. [ABSTRACT FROM AUTHOR]