Participatory experimentation involving farmers and researchers is often forwarded as a suitable approach for developing natural, human and social livelihood capital through technology, learning and empowerment, contributing in this way to resilience and sustainability. Learning in such processes takes place through interaction of farmers and researchers. Aspects like momentum, scientific rigor and farmer responsibility are, however, often at odds. This study explored how distribution of responsibilities affected outcomes for farmers and researchers. In a research project on participatory experimentation 16 farmer groups involved in five consecutive research cycles with the objective to increase crop yield. Essential control was handed over increasingly from the researchers to the farmer groups and in the course of their involvement responsibilities for farmers increased, whereas those of researchers decreased. Researchers included controls and replications and monitored different variables. In the course of their involvement responsibilities for farmers increased, whereas those of researchers decreased. Process of participatory experimentation, learning of farmers and change of attitude were documented systematically. Farmers’ and researchers’ involvement was analysed to reflect on their respective roles, the experimentation process and the outcomes achieved. Purposive involvement of farmers in all phases of the research resulted in relevant interventions, acquiring experimental skills, trust and commitment. Consequently, farmers’ natural, human and social capital increased. Researchers obtained insight in livelihood complexity, learned how to involve with farmers and to trust farmers’ competence and potential as co-researchers. The study concluded that delegating responsibilities to farmers in main stages of participatory experimentation is important to meet its objectives. At the same time, researchers involved in participatory experimentation should be sensitive to acknowledge farmers’ livelihood complexity. In this way both stakeholders will learn. Farmers, for example, by becoming more autonomous. Researchers by learning about, for example, general agronomic trends and social processes taking place. Exploiting the whole potential of participatory experimentation, therefore, requires a deliberate focus on farmer involvement.