HIV triply-diagnosed adults (those with chronic mental illness and substance abuse disorders) must rely heavily on public insurance to cover high annual medical costs (~$50,000). This study examines the nature and determinants of insurance coverage (including managed care) for this population, along with annual transitions in coverage. Relative to people living with HIV/AIDS in general, fewer triply-diagnosed adults rely on private coverage (3% vs. 30%), but their rate of being uninsured is only slightly lower (16% vs. 20%). More than one third of such adults below poverty are uninsured—a matter of significant policy concern since the annual income of this group is less than 10% of the amount needed to cover their expected medical expenses. Those with the lowest mental health status were disproportionately represented in managed care. While coverage appears relatively stable over time, those with low incomes and moderate mental health status may face barriers in securing Medicaid.