Objective: To identify key issues in the mental health policy development process in Cambodia that will contribute to an increased understanding of how mental health policy gets on the public policy agenda, how it stays there and why policy implementation fails or succeeds. The research was formative because mental health policy analysis is a young and newly emerging discipline.Method: A retrospective case study methodology was used to research the development of the draft Cambodian Mental Health Plan 2003–2022. Ten key informants involved in the policy development process were interviewed using a semistructured questionnaire designed to collect qualitative data about the policy formation process, stakeholders and context.Results: The research identified key issues influencing mental health policy development. These are the need to include the Ministry of Health (MoH) in the development of mental health plans, the significance of timing, the usefulness of mental health plans, the impact of the post-confli...