Empirical research demonstrates the highly variable outcomes resulting from Impact and Benefit Agreements (IBAs) between industry and Indigenous peoples in Australia and Canada. Differences in outcomes are far from trivial. Some Indigenous groups are reaping substantial economic benefits from agreements, while at the same time achieving a significant role in environmental management and adding to existing legal protection of Indigenous cultural heritage. Other agreements generate few economic benefits and do little to help minimise adverse cultural or environmental impacts. Some agreements impose significant constraints on exercise of Indigenous procedural rights under general legislation, others contain no such constraints. It is vital to explain such differences in outcomes in order to establish how more positive agreements can be achieved by all Indigenous peoples. This article argues that Indigenous political mobilisation, rather than any inherent flaws in the mechanisms of IBAs or differences in legal regimes, is vital in explaining variable outcomes. It considers how Indigenous capacity for political mobilisation can be enhanced and applied to negotiation of IBAs.