The CalSIM model is a tool for estimating the impact of the Affordable Care Act on employer and individual decisions to offer and obtain insurance in California. It was developed by the UC Berkeley Center for Labor Research and Education and the UCLA Center for Health Policy Research with funding from The California Endowment. The model provides data on changes in types of coverage for Californians under age 65 due to policy, the number of Californians under age 65 eligible for exchange subsidies, and characteristics of those individuals. It also provides data on the distribution of chronic conditions among Californians under age 65 in the exchange and individual market, as well as the number of newly eligible for Medi-Cal and their source of insurance.