Objective: To systematize the process of diagnosis and treatment plan formulations in participatory groups of users and professionals, called Fostering Groups, as an alternative to the conventional model of individual and sequential psychiatric consults, in the field of community mental health.   Material and Methods: The study was carried out in a community mental health center (CMHC) in Lima throughout the period January-December 2018. An action-research methodology was followed, in which proposals arising from the experiences were put into action to, then, critically analyze the and adjust them successively until reaching a point of standardization or consensus among the participants. Results: The participatory model was applied in 97% of the users during the observation period and the formulation of diagnoses and treatment plans during the Foster Group session was succ...