California jumped from 26th place to 14th overall in a new scorecard on health system performance from the Commonwealth Fund.
The scorecard shows between 2013 and 2015, California improved more than any other state.
The card is based on 44 indicators of health care access, quality, cost and outcomes.
California saw gains across all age groups.
For example, the percentage of three-year olds who were fully vaccinated rose. And the percentage of adults who went without care because of cost went down.
Doug McCarthy, the fund’s senior director of research, said the Affordable Care Act lead to a huge improvement in insurance coverage in California.
“The rate of uninsured children and working-age adults was cut in half, and this meant more than 2.7 million more adults and more than 420,000 children had health insurance that didn’t have it before," he said.
States that expanded Medicaid over the last few years saw the biggest improvements in this year's scorecard.
Vermont was the top-ranked state this year.