Participatory plant breeding (PPB) is a new concept in genetic improvement that, in contrast to conventional breeding, seeks to decentralize the development of varieties by involving farmers and other links in a crop's production chain. PPB intends mainly to answer the needs of small farmers of poor and marginal areas for whom conventional breeding cannot offer new varieties. Within the framework of a new research project, CIAT and CIRAD began, in April 2002, an upland-rice PPB programme, using population improvement methods. Although currently implemented in Nicaragua and Honduras, the programme will extend to all Central America and the Caribbean. This chapter presents the strategies proposed for this work, emphasizing initial diagnosis stages and participatory selection of already available material. The paper also describes stages of population improvement and extraction of improved lines to respond to the specific demands of each production zone. Finally, the expectations for the use of this methodology in the region are included.