The major aim was to describe occupational performance (OP) and social participation (SP) of mentally disordered offenders (MDO), and to compare professionals' and MDOs' appraisals of these abilities. Also, diagnostic groups and groups with/without substance related disorders were compared with regard to OP and SP. Self-report instruments (Capability to Perform Daily Occupations, Self-Efficacy Scale, Importance scale, Interview Schedule for Social Interaction), observations (Allen Cognitive Level Screen), and register data (Psychosocial and Environment Problems - Axis IV; Global Assessment of Functioning Scale - Axis V; Assessment Concerning Support and Service for Persons with Certain Functional Impairments) were utilized. Demographic and register data were collected from the Swedish National Board of Forensic Medicine. Seventy-four out of 161 incarcerated subjects (46%), selected consecutively after informed consent during a period of 16 months, were interviewed on their hospital wards. The MDOs reported some disability in performing occupations and participating in community life. However, they were satisfied with their performance and participation, implying limited awareness of their disabilities. The professionals judged the MDOs as having problems with social participation, and major, longstanding disablements in several areas. Subjects with schizophrenia scored lower in some OP and SP variables than did subjects with personality disorders and other mental disorders. The results suggest that a large proportion of MDOs need support to enable their community living.