The Huascarán Biosphere Reserve (HBR) is a tropical Andean protected area managed for “conservation with development,” one that is experiencing the common challenge of achieving both. Although there is little question that what was recognized as a global treasure in 1975, is a cultural landscape shaped by a long history of human occupation and management, the sustainability of indigenous agro-pastoral land use is now in question. My research was motivated by a desire to understand the environmental outcomes of indigenous livelihoods in an era in which they are increasingly transformed by the conservation and development agendas of national and international actors. I argue that failures of people-centered conservation are less to do with failures of local indigenous peoples to sustainably manage resources, and more to do with failures of policy-makers to accept responsibility for their role in shaping this outcome. Through the lens of cultural and political ecology, I show that successful biodiversity conservation in the HBR will demand greater attention to the specifics of common property management, and to the social, political, economic and environmental contexts in which communal institutions and their constituent decision-makers are embedded. This multi-scaled perspective takes a critical look at tourism and how it influences the herding practices of indigenous agro-pastoral households in the HBR. By drawing on common property theory, human behavioral ecology, and ecological fieldwork I show that enclosure in a protected area and the unsustainable growth of adventure tourism have had many unintended consequences. Throughout the dissertation I discuss these consequences as they are revealed through analyses of data collected during two years of fieldwork, explore their implications for indigenous livelihoods and biodiversity conservation in the HBR, and offer some potential solutions to avoiding negative outcomes in this unique protected landscape.