Numerous biological and psychological factors associated with impaired neurological functioning have been identified as common among the homeless, but there has been relatively little systematic examination of the cognitive functioning of homeless people. This study explored the neuropsychological functioning of 90 homeless men. There was great variability in their test scores, but the presence of possible cognitive impairment was detected in 80% of the sample. Average general intellectual functioning and reading abilities were found to be relatively low, and the incidence of impairments in reading, new verbal learning, memory, and attention and concentration was high. These findings suggest that the homeless men in this study had considerable assessment and treatment needs that were not being met by most of the health and social services offered to them.