This qualitative study assessed the frequency and subjective meaning of adverse experiences using case study analyses of interviews with 38 formerly homeless adults with co-occurring serious mental illness (SMI) and substance abuse histories. Adverse life events were inventoried using an adaptation of Lloyd and Turner’s (2008) 41-item checklist. Participants averaged 8.8 adverse events, with approximately one-third having experienced incarceration (37%), suicidality (32%), abandonment by one or both parents (30%), and death of their mother (34%). Cross-case analyses yielded 3 themes: social losses because of death and estrangement; the significance of chronic stressors as well as acute events; and the cumulative lifetime nature of adversity. Findings suggest that life course experiences of trauma and loss have a cumulative influence in the lives of this population in addition and in relation to SMI, substance abuse, and homelessness. In this context, the mental health recovery movement should address prior adverse experiences beyond comorbid diagnoses in this population.