This study expands on the Andersen-Newman health services utilization (HSU) model. In a community-based homeless sample (n = 363) baseline predisposing, enabling, and needs-based variables predicted hospitalization and ambulatory outpatient service utilization within 1 year after baseline. Standard predisposing and enabling variables were supplemented with latent constructs representing substance use, mental illness, poor housing status, social support, community support, and barriers to health care. Need is represented by baseline health status. Poor physical health, more barriers, drug use, African American ethnicity, less community support, and less education predicted hospitalization, the least desirable form of HSU. Poor health, female gender, a regular source of care, community support, drug use, and fewer alcohol problems predicted an office visit. Because outpatient visits for acute conditions provide an opportunity for generally neglected preventive services and health screenings, this study suggests convenient multiservice health-related programs for the homeless that include drug and alcohol treatment.