In this brief, SHARE grantee Deborah Chollet and her co-authors Allison Barrett and Amy Lischko analyze risk selection over time in Massachusetts' CommonWealth Care program, which serves low-income adults ineligible for Medicaid, much like a Basic Health Plan under the ACA.  Based on their findings, the authors offer lessons for other states considering whether to form a Basic Health Plan, looking at questions of program design, impacts on the commercial market, and financing and operations.