Objectives: To evaluate the Affordable Care Act’s dependent coverage mandate impact on insurance take-up and health services use through the second full year of implementation. Data: Medical Expenditure Panel Survey from 2006 to 2012. Study Design: Difference-in-difference regressions comparing pre-/postpolicy-outcome changes between 19- to 25-year-olds and 27- to 34-year-olds. Principal Findings: Following significant increases in 2011, insurance take-up among 19- to 25-year-olds leveled off overall in 2012. However, increases in coverage for Black young adults were higher in 2012 compared to 2011. Despite increased coverage, there is little evidence of an overall effect on health services use postmandate. Evidence points to increased doctor visits and emergency department visits among Hispanics in the first year postmandate. Conclusions: The Affordable Care Act young adult mandate led to significant gains in insurance take-up, though evidence suggests that the bulk of the gains occurred in the first year after the mandate. Gains for Black young adults appear to have picked up in 2012.