Scholars of Brazil’s public health system commonly note the intertwined roles that federal, state, and municipal governments play in delivering care, yet few studies systematically examine varying service performance in areas with overlapping mandates, such as state capitals. This study addresses that gap by developing and analyzing a novel measure of municipal primary care provision that accounts for the proportion of the population without access to private services in 11 large capital cities, then comparing them to the noncapital municipalities in their states. The study finds that capitals generally underperform the noncapital municipalities in primary service delivery. It then draws on a comparative case study in two major capitals, Salvador and Belo Horizonte, and their encompassing states to explore how a history of cooperative or adversarial relations between state and local governments conditions the impact of partisanship, participatory institutions, and public health activists on primary care delivery.