This brief describes the potential impact in Massachusetts of a proposed rule, released by the Department of Homeland Security in October 2018, to change the process by which it determines whether an immigrant is inadmissible to the United States or unable to adjust status because the person is likely to become a “public charge.” The proposed Public Charge Rule would mark a significant shift from current policy by defining a “public charge” as a noncitizen who receives one or more public benefits. This brief also provides an estimate of the scope of immigrants in Massachusetts who may be impacted by the proposed rule and what effect that could subsequently have, both directly and as a result of the “chilling effect,” on enrollment in particular benefit programs, including MassHeath and the Children’s Health Insurance Program (CHIP).