This paper assesses a long-term, on-going experience on participatory plant breeding (PPB) in food crops. It involves researchers, extension agents, and producers' organizations whose members live in marginal and poor areas in five Central American countries. This experience confirms the feasibility, despite adverse conditions, for implementing novel institutional arrangements, renewed research approaches and practices leading to the emergence of sustainable innovations processes and systems which reconcile production and conservation. By combining scientific and farmer knowledge, the project stakeholders were able to jointly develop a large array of varieties suited to a diversity of unfavourable local environmental and socioeconomic contexts, an array much larger indeed than what was available locally before. Over time, the project evolved beyond collaboration and entered into a true partnership, by developing governance mechanisms which allow a greater protagonism from farmers' organizations. Nevertheless, this experience also illustrates limitations and challenges of such approaches, especially when social demand for extending and scaling up increase, nurtured by the early successes and know-how achieved during the initial phases of the project. To respond to this challenge, major bottlenecks need to be addressed, such as ensuring the hiring of a young generation of PPB scientists to continue the work of their elders, and the necessary funding for these activities. This would however imply that adequate policy support indeed exists for science to effectively contribute to poverty mitigation.