The high proportion of veterans among homeless men is perplexing given the opportunities associated with military service and the benefits long available to veterans. One little-examined risk factor for homelessness is that many homeless men may have received punitive discharges that result in ineligibility for Department of Veterans Affairs benefits. Data from a sample of homeless male veterans with mental illness enrolled in the Access to Community Care and Effective Services and Supports Program are used to examine punitive discharges as a risk factor for homelessness and to compare veterans with punitive and non-punitive discharges on premilitary, military, and postmilitary experiences. Only 7% of homeless veterans received punitive discharges. Pre-military experiences are associated with such discharges, but military experiences are not. Although a punitive discharge is a strong risk factor for subsequent homelessness, such discharges primarily reflect premilitary vulnerabilities and are a relatively minor reason for homelessness because they affect a small proportion of the general veteran population.