Background: In recent decades research has reported high rates of cognitive difficulties in individuals experiencing homelessness. Thus far, these difficulties have been linked with higher instances of traumatic brain injuries (TBIs), substance misuse, and mental health (MH) issues in this group compared to the general population. In addition to existing structural and systemic barriers, cognitive difficulties can hinder a person’s exit from homelessness. Method: A scoping literature review was conducted to investigate whether intellectual disability (ID) may contribute to level of cognitive difficulties observed in homelessness. An exploratory cross-sectional study was carried out to provide a profile of the neuropsychological issues in a small sample of individuals experiencing homelessness and their use of services. The methodology employed addressed key issues in the field of homelessness research. Results: The review identified seven studies exploring homelessness and ID with the proportion of ID reported ranging from 5.6% to 39% across samples. The field study further supported the accrual of multiple vulnerabilities in homelessness including cognitive impairment and TBI. Participants had high attendance at acute services, namely Accident & Emergency (A&E), while specialist MH and brain injury services were rarely if ever used. The methodology employed was tolerated well by participants and provides a template for future research which can be further developed. Conclusions: This thesis highlights the cognitive impairment in homelessness. Further research, building on the methodology employed in this study, can investigate how the different issues identified (e.g. TBI and MH difficulties) relate to the cognitive impairment observed and how best to support them.