This paper interrogates pathways into multiple exclusion homelessness (MEH) in the UK and, informed by a critical realist theoretical framework, explores the potential causal processes underlying these pathways. Drawing on an innovative multistage quantitative survey, it identifies five experiential clusters within the MEH population, based on the extent and complexity of experiences of homelessness, substance misuse, institutional care, street culture activities and adverse life events. It demonstrates that the most complex forms of MEH are associated with childhood trauma. It also reveals that the temporal sequencing of MEH-relevant experiences is remarkably consistent, with substance misuse and mental health problems tending to occur early in individual pathways, and homelessness and a range of adverse life events typically occurring later. The strong inference is that these later-occurring events are largely consequences rather than originating causes of MEH, which has important implications for the conceptualisation of, and policy responses to, deep exclusion.