Using Synthetic Control Method for comparative case studies, we estimate the causal impacts of the Massachusetts Health Care Reform (MHR) enacted in 2006 on the sources of insurance coverage. We find that MHR caused two main sources of expansions, viz., employer sponsored insurance (ESI) and Medicaid, with no evidence of crowding out. The expansion in ESI mirrors the economic cycles. The overall expansion in coverage of over half-a-million is distributed approximately 60:40 between ESI and Medicaid. Other sources of coverage such as direct purchase and Medicare, in a causal sense, were unaffected by MHR.