The Cumulative Environmental Management Association (CEMA) was formulated in 1998 by Alberta Environment to provide a multi-stakeholder, consensus-based recommendation forum for managing cumulative effects of oil sands development in the Athabasca region. The Association was designed with 'stakeholders' in mind, rather than First Nations 'rights' holders, creating frustration and tension between the Association and Aboriginal communities. This resulted in the withdrawal of the Athabasca Chipewyan First Nation (ACFN) and the Mikisew Cree First Nation (MCFN) from the Association process. Through qualitative interviews, results depict the Association's ineffective management framework, the lack of Aboriginal power or influence, inadequate Crown consultation, and the failure to recognize legislated Aboriginal rights, as major factors contributing to the First Nations withdrawal. This study includes recommendations for the meaningful contributions of Aboriginal people in environmental monitoring and the promotion of sustainable development in and around their traditional lands.