can you summarize this The health economics community has responded robustly to the exciting opportunities for new analysis made available by the ACA. In the decade since the law was passed and the five years since it became fully effective, dozens of studies have emerged to explore and evaluate a wide variety of the law's impacts. These studies have covered a broad range of areas, and we have learned much. One notable feature from our perspective is that this literature has been generally empirically sophisticated, recognizing the challenges in causally estimating the impact of policies on outcomes. Most of the studies reviewed here have not relied on simple time series or cross-sectional comparisons but have used more sophisticated quasi-experimental approaches, with a variety of plausible control groups whenever possible. The studies of the Medicaid expansions have been particularly convincing in this context, attributable to both the natural control group created by the state-level variation in expansion decisions, and the generally robust analysis of preACA trends and multiple other specification checks in most of the papers cited here. More good news is that we have learned an enormous amount in just a short period. The evidence reviewed here clearly demonstrates that the ACA led to major Journal of Policy Analysis and Management DOI: 10.1002/pam Published on behalf of the Association for Public Policy Analysis and Management 1046 / The Affordable Care Act's Effects