Patient and Public Involvement and Engagement (PPIE) has been increasingly encouraged in health services and research over the last two decades. Particularly strong evidence has been presented with regard to the impact that PPIE has in certain research areas, such as mental health. Involving the public in mental health research has the potential to improve the quality of research and reduce the power imbalance between researchers and participants. However, limitations can be frequent and include tokenistic involvement and lack of infrastructure and support. Nevertheless, PPIE has the potential to impact mental health research in the Latin American context, where existing policies already support public involvement in health research and where the burden of mental disorders is significant. There are many lessons to learn from the evidence of PPIE in other regions. Latin America now has the opportunity to tackle one of today's most important issues: effective health care service delivery for all, based on evidence from comprehensive health research.