Over the past 15 years the Tanzanian government has promoted participatory forest management (both joint forest management and community-based forest management) as a major strategy for managing natural forests for sustainable use and conservation. Such management is currently either operational or in the process of being established in > 3.6 million ha of forest land and in > 1,800 villages. Data from three case studies of forests managed using participatory and non-participatory forest management approaches suggest that community involvement in forest management is correlated with improving forest condition. In our first case study we demonstrate increasing basal area and volume of trees per ha over time in miombo woodland and coastal forest habitats under participatory forest management compared with similar forests under state or open access management. In our second case study three coastal forest and sub-montane Eastern Arc forests under participatory forest management show a greater number of trees per ha, and mean height and diameter of trees compared to three otherwise similar forests under state management. In our third case study levels of cutting in coastal forest and Eastern Arc forests declined over time since initiation in participatory forest management sites. We conclude that participatory forest management is showing signs of delivering impact in terms of improved forest condition in Tanzanian forests but that further assessments need to be made to verify these initial findings.