Community health worker (CHW) programs are implemented in many low‐ and middle‐income countries such as Brazil to increase access to and quality of care for underserved populations; CHW programs have been found to improve certain indicators of health, but few studies have investigated the daily work of CHWs, their perspectives on what both helps and hinders them from fulfilling their roles, and ways that their effectiveness and job satisfaction could be increased. To examine these questions, we observed clinic visits, CHW home visits, and conducted semistructured interviews with CHWs in 7 primary care centers in Brazil—2 in Salvador, Bahia, and 5 in São Paulo, SP—in which CHWs are incorporated into the work of all primary care health teams. In addition to enhancing communication between the medical system and the community, CHWs consider their key roles to be helping persuade community members to seek medical care and increasing health professionals' awareness of the social conditions affecting their patients' health. Key obstacles that CHWs face include failure to be fully integrated into the primary care team, inability to follow‐up on identified health needs due to limited resources, as well as community members' lack of understanding of their work and undervaluing of preventative medicine. Increased training, better incorporation of CHWs into clinic flow and decision making, and establishing a clear community awareness of the roles and value of CHWs will help increase the motivation and effectiveness of CHWs in Brazil.