Objective This study presents evidence on how the dependent provision in the Affordable Care Act (ACA) differentially affected coverage for young adults across states and population subgroups. Study Design/Methods/Data The data derive from the American Community Survey. Using a difference‐in‐difference design, we compare the target population (ages 19–25) with a control group (ages 26–29). Principal Findings Net private health insurance coverage increased by 4.6 percentage points and overall coverage increased by 4.2 percentage points for people aged 19–25; more for Whites than non‐White subgroups. Conclusions and Implications Changes in coverage for states appear driven by demographics rather than the existence of prior dependent expansions by the state. Disparities in health care coverage remain, but the absolute level of coverage is improving.