Adults with an autism spectrum condition (ASC) experience a range of socio-economic disadvantages across the life course including; social isolation, low educational attainment, unemployment, and poverty. These outcomes are also risk factors for homelessness. Whilst emerging research in the UK suggests a disproportionate amount of autistic adults experience homelessness, little is known about what predisposes autistic people to homelessness and how best to support them. Additionally, it is likely that many homeless autistic adults are undiagnosed and unable to access suitable support. Therefore, in order to examine the relationship between autism and homelessness, it is first imperative to explore how ASC is defined and diagnostic criteria applied. This thesis presents a multi-causal, social interpretational model of autism which posits that ASC has no singular biological marker and that diagnostic boundaries are historically and socially constructed. From this position, the label of autism still has meaning, as it describes a set of behaviours which sit outside of normative ideals. Using this model as a framework, study recruitment involved identifying adults with a clinical diagnosis of autism, or those who self-identified as autistic, who had experienced homelessness. Ten participants were accessed through homelessness services and consented to take part in the study. Each participant took part in two to three narrative interviews which centred on their life history and experiences of homelessness. Thematic analysis revealed complexity of life experience, with participants reporting abuse in childhood, multiple co-occurring conditions, historic or current substance dependency, or imprisonment. The majority of participants experienced episodic homelessness, sometimes from childhood, which was usually triggered by relationship breakdown coupled with lack of financial and social support. Participants found it difficult to navigate support systems and statutory accommodation provision was insufficient when considering social and sensory needs. In terms of contributors to homelessness, analysis of narratives revealed social rejection across the life course which impeded participants' ability to do well at school, find and maintain employment, access welfare and expand support networks. Participants responded to this exclusion in two distinct ways; by attempting to mask autistic behaviours in order to fit in, or by rejecting social expectations and withdrawing from society. Whilst neither strategy mitigated against homelessness, the majority of participants went on to renegotiate their autistic identities which enabled them to become self-advocates, challenging discriminatory practice and exclusion. This thesis reinterprets study findings using a critical realist framework. Exclusion across the life course is explained through the lens of Critical Disability Studies, wherein disabled persons are rejected for not meeting normative ideals. This thesis goes on to engage with Dis/human Theory, explaining how the labelling of individuals as autistic can be utilised as a position from which to challenge structural inequities. Study findings suggest a need for increased awareness of autism and flexibility of provision in education, employment, welfare, and homelessness services. Whilst some adaptations can be made within existing frameworks, significantly reducing risk of homelessness for autistic adults requires deeper structural changes and the repositioning of accepted forms of personhood and normalcy.