This article examines the potential of impact and benefit agreements (IBAs) between Aboriginal peoples and industry to effectively monitor the implementation of agreement provisions and the social, cultural and environmental impacts of extractive projects. The role of IBAs as ‘monitoring instruments’ is especially important given the withdrawal of neoliberal governments from their traditional role as environmental regulators. Case studies from Australia and Canada indicate that IBAs have considerable potential to effectively monitor project impacts and delivery of project benefits, but a broader analysis of IBAs in both countries shows that this potential is often not realised. This is in part because of the failure of state authorities to play a supportive role, and because financial constraints and weaknesses in organisational capacity undermine effective implementation of IBAs, including their monitoring provisions. Both the success of Aboriginal peoples in securing positive state involvement, and in realizing the potential of IBAs as monitoring mechanisms, is shown to depend crucially on Aboriginal political mobilisation.