This study examines the effects of New Yorks Health Care Reform Act of 2000 on the insurance coverage of eligible adults using the National Health Interview Survey (NHIS) and the Current Population Survey (CPS). We find a significant reduction in uninsurance for parents but for childless adults, for whom the coverage expansion was narrow, we find no evidence of a significant decline in uninsurance. The paper also explored the feasibility of using the NHIS as a data source for studies of state coverage policy changes, concluding that the NHIS is indeed a sound data source for such studies. Health Services Research, Vol. 42, No. 6, 2007, pp. 2332-2353.