This paper reviews the development of Aotearoa-New Zealand’s (New Zealand’s) specialist Mental Health and Addiction Services (MH&A Services) and Mental Health and Addiction plans (MH&A Plans) to improve the mental well-being of all New Zealanders. It does so in the context of New Zealand’s 2022 health reforms, and the government’s response to its 2018 Inquiry into MH&A (He Ara Oranga). First, the context for reform is described, including New Zealand’s sociodemography, existing data monitoring systems, mental health epidemiology and a current overview of its specialist MH&A Services. The findings of the He Ara Oranga Inquiry and the goals of the MH&A plans are then outlined, along with progress in establishing new initiatives related to them. Finally, challenges to the new direction for New Zealand’s MH&A system are reviewed, with possible strategies to address them and other key implementation challenges involving the separation and operationalisation of the main strategies of MH&A plans. A high-level view of MH&A Services is taken, rather than one detailing speciality services such as age-related, cultural or addiction services.