Despite well-documented need, little is known about the HIV prevention services provided to adults with serious mental illness in the public mental health system. This study examined the types, frequency, and client-level correlates of HIV prevention services provided to a representative sample of clients in five public mental health care programs. Although results indicate that HIV prevention care is infrequent, clients identified as being at higher risk for HIV infection reported receiving prevention interventions more frequently. However, both the clients’ gender and the service setting influenced the types and frequency of services that clients received.