DISCLAIMER: The present Project Deliverable has been submitted to the European Commission for review. The information and views set out in this report are those of the author(s) and do not necessarily reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor any person acting on their behalf may be held responsible for the use which may be made of the information contained therein. This policy brief tables recommendations to strengthen mental health social support networks, as a result of the design and implementation of a new Citizen Social Science (CSS) project. Social support is a positive factor within mental health recovery, while also acting against social exclusion. However, evidence on how to fully harness its potential is still lacking. The “CoAct for Mental Health” project has been co-designed and directly driven by Co-Researchers, people with mental health problems and their families. The intrinsic and transformative value of personal lived experiences of mental health problems is extended with the methods and tools presented. CSS makes it possible to implement an inclusive and multi-level participation model, based on cooperation. This involved launching a chatbot to invite all citizens to participate in the CSS research and deploying collective data interpretation methodologies to include Co-Researchers in the results discussion and in drawing conclusions to make recommendations and support specific demands. Within the local context of Catalonia, specific recommendations are made, which will be mainstreamed within the National Mental Health Pact. At a more global level, recommendations to include CSS tools and methodologies are made to the mental health research community.