Participatory guarantee systems (PGSs) have emerged as a response to exclusion and intermediation processes involving third-party certification, which is currently the only guarantee system recognised by the European Union for organic food. Despite their unofficial recognition, PGSs are developing and generating shared frameworks of action. In this research, through three certification bodies (two public and one private) and eight PGSs in Spain, we investigate the similarities and differences between the procedures and tasks that both systems develop in order to generate trust in the decision-making structures involved and the responsibilities on which they are based. While the overall organisation of the systems is very similar, there are profound differences in their decision-making: their procedures and who participates in them. The differences we highlight lead us to argue that PGSs effectively solve the exclusion problems that third-party certification generates. Specifically, they offer lower costs and more accessible bureaucracy. They also generate and strengthen, through trust-building, the links and processes of local self-management and empowerment. However, developing PGSs demands much time and dedication, and their official regulation is complex, so it is difficult to predict that they will be widely adopted.