We examine how community health workers (CHWs), while working as links between doctors, nurses and vulnerable groups, participate in the social construction of citizens in the implementation of Brazil’s primary healthcare policy. Drawing on interviews and a vignette experiment with CHWs in the city of São Paulo, we show that perceptions of CHWs about the vulnerability and agency of health system users impact upon their referrals to other levels of service. Judgments about the socioeconomic, cultural and moral conditions of families determine different referrals – on the one hand, to practices based on persuasion and respect for individual choices; on the other, to ‘top-down’ or forcible interventions. While implementing the same healthcare policy, CHWs construct users as (responsible) agents or (helpless) targets, thus determining different pathways in the health system and shaping the relationship between citizens and the state. Brazil’s primary health policy, while seeking to tackle vulnerability, is also a site where social representations are reproduced that contribute to the denial of the agency of citizens deemed more vulnerable and to the definition of their bodies as sites for state intervention.