BACKGROUND: Homelessness encompasses a wide spectrum of experience. Rough sleepers and people attending homeless shelters have been found to be at an increased risk of mortality. It is unclear whether risks are also elevated in those squatting, living temporarily in low-cost hotels or 'sofa-surfing' with friends or family members. This study examines mortality in a representative nationwide sample of people who have slept rough, squatted, lived in shelters or low-cost hotels and sofa-surfed. METHODS: Using unpublished data from two national birth cohorts, namely the National Child Development Study and the 1970 British Birth Cohort study, Cox proportional-hazards models and random-effects meta-analyses were used to analyse associations between homelessness and different types of homeless experience (rough sleeping, squatting, staying in a homeless shelter or low-cost hotel, and sofa-surfing) and mortality. RESULTS: Out of the 23 678 participants, 1444 (6.1%) reported having been homeless and 805 (3.4%) deaths occurred. Homelessness was associated with an increased risk of mortality [hazard ratio (HR) 1.68, 95% confidence interval (CI) 1.24-2.26]. Mortality risk was raised across the spectrum of homeless experience, from sleeping rough (HR 4.71, 95% CI 2.38-9.30), to squatting (HR 6.35, 95% CI 2.73-14.75), staying in a homeless shelter (HR 4.89, 95% CI 2.36-10.11), staying in a low-cost hotel (HR 3.38, 95% CI 1.30-8.79 through to sofa-surfing (HR 2.86, 95% CI 1.84-4.42). Associations remained after separate control for socio-economic status, mental health, substance use, accidents and assaults, and criminality. CONCLUSIONS: Mortality rates were raised across all types of homeless experience. This included squatting and sofa-surfing that have not previously been reported. Studies that have omitted the less severe, but more prevalent, use of low-cost hotels and sofa-surfing may have underestimated the impacts of homelessness on mortality.