During the 1980s, when a flexible approach to research, known as farmer-back-to-farmer, was developed, the International Potato Center (CIP) became famous for participatory research. Subsequently it appeared to have lost leadership in this field. This article documents participatory research activities in CIP over the past thirty years to find out what happened. Even in the 1980s, implementation of participatory research was actually limited. Participatory research in the center grew unevenly, with little clear encouragement from the CGIAR. Decentralization of social scientists in the 1990s led to the fragmentation of participatory research and, in the absence of any clear champion, it seemed that it might wither away. Recently, increasing interest in IPM, donor support, and the recruitment of international staff who have been exposed to other currents of participatory research and training has led to a revival of interest. This needs to be carefully nurtured to ensure that the flexibility for which participatory research in CIP earlier gained world renown is retained. © 2001 Kluwer Academic Publishers.