Mental illness is prevalent in the homeless population, and research suggests that personality disorders may account for a significant proportion of psychopathology. The review proceeds to an appraisal of the particular features characteristic of personality disorder that may contribute to homelessness, based on Maguire, Keats & Sambrook's (2006) model. These factors may not only increase susceptibility to homelessness, they may also act as barriers to exits from homelessness, to the extent that individuals are at serious risk for long-term, chronic homelessness. The current approach to diagnosing personality disorders may be disadvantageous to homeless individuals and also yield limited information about psychopathology. The debate between categorical and dimensional models of understanding personality disorders is presented, along with a critical evaluation of each approach. Although the present categorical approach does have certain advantages, there appear to be a number of deficiencies pertaining to the reliability of diagnoses. There is promising evidence advocating a dimensional approach and this should be given serious consideration. Given the low uptake of services and high dropout from treatment among the homeless population, alternative approaches including therapeutic communities and treatment in accommodation are reviewed. Greater funding to provide psychological therapies within accommodation and to provide suitable training for staff members (for instance, in CBT) is necessary to increase uptake and completion of treatment in a vulnerable population with severe and complex needs. There may also be potential value in prevention programs designed to enhance personality resilience and adaptive capacities.