Action research in partnership combines knowledge production, transformation of social realities and strengthening individual and collective skills. The book gives the basics of action research partnership in agriculture and the elements to put into practice such an approach. It highlights not only the theoretical but also practical issues raised by this threefold. The book draws on a wide range of experience in agriculture in developing countries, illustrating how practitioners have responded to the challenges of an approach that is always reinventing contexts. Concrete examples are given, taken from experiments now in Brazil, now in Cameroon, Vietnam, Senegal, .... This manual of over 200 pages is intended for researchers, rural development experts and representatives of the rural world facing the resolution of complex problems posed by the rural development in agriculture in developing countries.