Federally qualified health centers (FQHCs) provide care in underserved areas, regardless of an individual’s ability to pay, and can be a critical source of care for children with public or no insurance who have greater difficulty getting care from providers in the community. In 2013, about one‐third of FQHC patients nationally were children. The Affordable Care Act (ACA) increased federal funding for FQHCs by $11 billion between 2011 and 2015, with the policy goal of increasing access to care for underserved populations. We examined the effects of the increased funding for FQHCs on children and adults in Massachusetts.We used 2010‐2013 claims data from the Massachusetts All Payer Claims Database (APCD) to examine changes in visits to FQHCs among enrollees included in the APCD (Medicaid, commercial insurance, and visits by uninsured residents covered by the Health Safety Net).We obtained FQHC funding information from the Uniform Data Set. To assess the impact of changes in funding (federal and state) on FQHC visits, we used a shift‐share instrument to measure local exposure (5‐digit ZIP code‐level) to changes in funding: we weighted the year‐to‐year percentage change in FQHC funding by the local share of each FQHC’s patient population in 2009 and summed across FQHCs in the ZIP. We used a multivariate linear regression model to assess the association between the year‐to‐year percentage change in local exposure to FQHC funding and the percentage change in the total number of FQHC visits or number of residents with FQHC visits in 2010‐13, adjusting for each ZIP codes’ demographic and health characteristics (eg, age, median comorbidity scores). We used similar models to examine changes in ED visits and stratified models for children vs. adults. Models were weighted by the ZIP code population, and standard errors were clustered by ZIP.Children (N = 1 145 205 in 2010) and adults (N = 5 038 277 in 2010) included in the Massachusetts APCD and 31 FQHCs that received funding from the Community Health Center Fund between 2010 and 13.Annual pediatric visits at MA FQHCs increased by 10% and adult FQHC visits by 14% from 2010 to 2013. Those with vs. without FQHC visits were more likely to have Medicaid insurance (67% vs. 17%) and live in low‐income neighborhoods (37% vs. 22%). Increased visits to FQHCs by children were associated with increases in FQHC funding, for example, +6.8 percentage point (95% CI [1.7, 11.8]) with +1SD change in prior year funding. ED visits by children also decreased with greater local exposure to FQHC funding, for example, −1.3pp ([−2.4, −0.2]) with +1SD change in prior year funding. FQHC visits for adults did not vary significantly with FQHC funding, but ED visits decreased by a similar magnitude as children.Increases in FQHC funding resulted in significant increases in use of FQHC services, especially for children. ED visits for children and adults also decreased with greater FQHC funding.The ACA funding increases for FQHCs appeared to increase access to community health center services for low‐income children and reduced costly emergency department care for underserved communities.Agency for Healthcare Research and Quality.