Although the design of participatory processes to manage social-ecological systems needs to be adapted to local contexts, it is unclear which elements of process design might be universal. We use empirical evidence to analyze the extent to which context and process design can enable or impede stakeholder participation and facilitate beneficial environmental and social outcomes. To explore the role of design and minor variations in local context on the outcomes of participatory processes, we interviewed participants and facilitators from 11 case studies in which different process designs were used to select sustainable land management options in Spain and Portugal. We analyzed interview data using quantitative and qualitative approaches. Results showed that although some aspects of local context affected process outcomes, factors associated with process design were more significant. Processes leading to more beneficial environmental and social outcomes included the following: the legitimate representation of stakeholders; professional facilitation including structured methods for aggregating information and balancing power dynamics among participants; and provision of information and decision-making power to all participants. Although processes initiated or facilitated by government bodies led to significantly less trust, information gain, and learning, decisions in these processes were more likely to be accepted and implemented. To further test the role of context in determining the outcomes of participation, we interviewed facilitators from a process that was replicated across 13 dryland study sites around the world, reflecting much greater national variations in context. The similarity of outcomes across these sites suggested that the socio-cultural context in which the process was replicated had little impact on its outcomes, as long as certain design principles were fulfilled. Overall, our findings provide a solid empirical basis for good practice in the design of participatory processes in the management of social-ecological systems.