This paper offers a historical examination of the ways in which advocacy strategies and tactics have shifted in relation to political opportunities, using a case study of a hydroelectric dam project in the Brazilian Amazon, known as the Belo Monte Dam. Drawing on over three decades of resistance by transnational activist coalitions, the paper looks at how new tactics and political alignments have altered the dynamics of activism and norm diffusion in Brazilian domestic environmental, human rights and development policies. The paper argues that current theories of norm diffusion inadequately explain backslides and tend to underestimate the complexity of domestic political alignments. The case adds political insight to our understanding of the relationship of transnational advocacy strategy to environmental and human rights political realities in Brazil.