In a world of increasing demands for biodiversity information, participatory biodiversity assessment and monitoring is becoming more significant. Whilst other books have focused on methods, or links to conservation or development, this book is written particularly for policy makers and planners. Introductory chapters analyze the challenges of the approach, the global legislation context, and the significance of the Millennium Ecosystem Assessment. Specially commissioned case studies provide evidence from 17 countries, by 50 authors with expertise in both biological and social sciences. Ranging from community conservation projects in developing countries to amateur birdwatching in the UK, they describe the context, objectives, stakeholders and processes, and reflect on the success of outcomes. Rather than advocating any particular approach, the book takes a constructively critical look at the motives, experiences and outcomes of such approaches, with cross-cutting lessons to inform planning and interpretation of future participatory projects and their contribution to policy objectives.