BackgroundThe Zanzibar Ministry of Health and Social Welfare, concerned about mental health in the country, requested technical assistance from WHO in 1997.AimsThis article describes the facilitation over many years by a WHO Collaborating Centre, of sustainable mental health developments in Zanzibar, one of the poorest countries in the world, using systematic approaches to policy design and implementation.MethodsBased on intensive prior situation appraisal and consultation, a multi-faceted set of interventions combining situation appraisal to inform planning; sustained policy dialogue at Union and state levels; development of policy and legislation, development of strategic action plans, establishment of intersectoral national mental health implementation committee, establishment of national mental health coordination system, integration of mental health into primary care, strengthening of primary-secondary care liaison, rationalisation and strengthening of secondary care system, ensuring adequate supply of medicines, use of good practice guidelines and health information systems, development of services for people with intellectual disability, establishment of formal mechanism for close liaison between the mental health services and other governmental, non-governmental and traditional sectors, mental health promotion, suicide prevention, and research and development.ResultsThe policy and legislation introduced in 1999 have resulted in enhanced mental health activities over the ensuing decade, within a setting of extreme low resource. However, advances ebb and flow and continued efforts are required to maintain progress and continue mental health developments. Lessons learnt have informed the development of mental health policies in neighbouring countries.ConclusionsA multi-faceted and comprehensive programme can be effective in achieving considerable strengthening of mental health programmes and services even in extremely low resource settings, but requires sustained input and advocacy if gains are to be maintained and enhanced.