Community engagement (CE) has increasingly been recognized as a critical element for successful health promotion and intervention programs. However, the term CE has been used to mean different things in different settings. In this article, we explore how CE has been conceptualized in the field of mental and brain health in Kilifi County, Kenya. We used ethnographic methods encompassing focused group discussions, key informant interviews, and observations with 65 participants, purposively recruited from Kilifi County. Data were transcribed verbatim and thematically analyzed. Our findings show that community members and stakeholders had diverse perceptions of and experiences with CE. Factors such as trust between researchers and community members, sensitization, and awareness creation were key for acceptance of research projects. Partial involvement in research, lack of access to information, poverty and socio-economic challenges, and financial expectations from researchers hindered CE and led to resistance to participation in research projects. For effective CE, there is a need to work closely with community gatekeepers, create awareness of the research projects, use local languages, and ensure continuous engagement that promotes equitable research participation. Our findings suggest that tacit knowledge, context, and mechanisms for research are all critical features of CE and should be considered to enhance acceptance and sustainability of mental and brain health interventions in Kenya.