The material presented in this book is largely drawn from the Food and Agriculture Organization's research programme on ‘Using Markets to Promote Sustainable Development’ that seeks to provide a better understanding of the interaction between agricultural markets and the use and conservation of crop genetic resources. The conservation and enhancement of agricultural biodiversity is recognized as a critical element in sustaining the flow of agricultural innovations and enhancement of productivity. Although crop genetic resources have several public good characteristics, market-based arrangements and incentives are being increasingly suggested as mechanisms to support the on-farm conservation of agricultural biodiversity. Informal agricultural seed markets still play a dominant role in seed supply in developing countries, but there is relatively little empirical work on how these markets work and the outcomes they achieve. This book provides a set of five rich case studies from Bolivia, India, Kenya, Mali and Mexico that provide valuable empirical insights into the operation of these markets and how they affect farmers' choice of varieties. A key message from the book is that developing effective strategies to improve the working of informal agricultural markets calls for a good understanding of the diversity of their characteristics, social context, functions and outcomes. The case studies illustrate both the limitations and opportunities of agricultural market development to support the conservation of agricultural biodiversity.