This dissertation explores the impacts of participatory conservation on gender structure in the Mamirauá Sustainable Development Reserve (MSDR), Amazonas, Brazil. Generally, I am concerned with the social consequences of conservation initiatives for protected area residents-to what extent the participatory model is equitable for local people, particularly sub-groups such as women, and how gender hierarchies are affected by program participation. Using ethnographic and other qualitative methods, I investigate the transformation and reproduction of gender relations by analyzing how conservation initiatives shift the gender division of labor, empower women, and impact family and community organization. This study shows that participatory conservation projects, which introduce or reinforce exogenous institutions and cultural ideologies such as a cash economy, wage labor, democratic representation, organized civic engagement, and egalitarian ideology, create fundamental, unintended shifts in local social organization. These changes have important implications for human well-being and equality as well as long-term social and environmental sustainability. My findings show that gender relations are shifted in a more egalitarian direction as women engage in new economic activities, create political space, and interact with outside social carriers, yet, in many ways, traditional gender relations, including norms and hierarchies, are reproduced. Programs remain focused on a traditional gender division of labor, reinforce cultural expectations regarding women's responsibility as the main providers of child care for dependent children, and do not address barriers to women's participation and leadership at the social-relational level, i.e., within marriages and families-both primary production sites of gender inequality. The changes in social organization produced through sustainable development and conservation projects cannot be ignored from a conservation perspective, as these shifts affect the ability of women, potentially a strong source of conservation support, to participate as conservationists and active natural resource managers. Last, the introduction and reinforcement of these modern institutions creates such fundamental shifts in social organization that the prospects for long-term sustainability of the Sustainable Development Reserve (SDR) model are questionable. Examples of concerning changes include shifts in household structure and the attenuation of family cohesion as men and women leave their communities for days and weeks at a time for paid labor in conservation-related jobs; decreased agricultural production; a decline in communal traditions of labor reciprocity resulting from the loss of available adult workers within the household and community; loss of intergenerational knowledge regarding natural resource use and traditional economic activities; as well as shifts in livelihood and material aspirations among younger generations.