The Tax Cuts and Jobs Act (TCJA) eliminated the ACA's “shared responsibility payment,” which penalized those who failed to comply with the requirement to purchase health insurance. In this article the authors explain efforts in several states to respond to this change by adopting individual health insurance mandates at the state level. Although there are good reasons to think that states may be reluctant to consider establishing their own mandates, New Jersey, the District of Columbia, and Vermont quickly joined Massachusetts in establishing such measures in 2018. In 2019 California and Rhode Island enacted state-level mandates. Four other states—Maryland, Connecticut, Hawaii, and Washington—formally considered mandates but have not enacted them. The authors compare the policy debates among these states and one other state, New York, which has not seen a legislative proposal for a mandate despite its strong support for the ACA. Their analysis explores the dynamics within the US federal system when a key component of a complex and politically salient national initiative is eliminated and states are left with many policy, political, and administrative questions of what to do next.