The Resource Management Act (1991) (RMA) was heralded as internationally ground-breaking for its integrated approach, and for cementing 'sustainable management' as its overarching purpose. It was ground-breaking also for its recognition of First Nations’ rights and values. This includes directing decision-makers to recognise and provide for the relationship of Māori and their culture and traditions with their ancestral lands, waters and treasured resources, to have particular regard to Māori customary practices, and to take into account the principles of the Treaty of Waitangi. The RMA provides for councils to transfer or delegate functions and powers to Māori, and for joint management arrangements. In 16 years as environment officer for my iwi, I witnessed the failure of the RMA to protect Māori values and interests. This experience prompted me to undertake research to thoroughly investigate outcomes of the operation of the RMA for Māori. Two questions framed my research; the first asking whether kaitiaki have been empowered by the Māori provisions in the RMA, and the second seeking to determine overall outcomes for Māori from the Act. Assessing such outcomes required an understanding of Māori values and interests, evaluation of the law, of the statutory plans that govern council administration of the RMA, implementation of these by councils and the Crown, and their treatment by the courts. To answer the two questions I present in this thesis a geographically focused study of two take (causes or significant issues) at Whangamatā, the construction of a marina, and the removal of mangroves. I compare Ngāti Whanaunga experiences with those of Māori nationally. By doing so I provide the evidence base for an 'overall broad judgement' (as the RMA requires) that despite apparent empowerment by the Act and its statutory plans, Māori have suffered widespread and significantly negative outcomes under the RMA. Rather than being empowered, Māori struggle to participate in planning processes, and see ancestral values and interests eroded by waves of resource consent processes, in which effects on Māori are little considered.