Compulsory interventions are widely used in general adult psychiatry for the treatment and care of patients with severe mental illness. While involuntary hospitalisation is established in practice around the world, the use of compulsory interventions outside of hospital â so called community treatment orders (CTOs) â is a more recent development. Three randomised controlled trials of CTO effectiveness have been conducted to date finding no benefits for patients in terms of reduced relapse and readmission to hospital. However, these trials have been relatively short (11-12 months) and focused almost exclusively on CTO effects on clinical functioning and service use. Little attention has been given to patients' social outcomes and broader welfare despite their recognised importance. A sub-sample (n = 121) from the Oxford Community Treatment Order Evaluation Trial (OCTET) were interviewed 48-months after randomisation to assess whether the duration of the CTO intervention was associated with more or less favourable social outcomes at follow-up. Social outcomes were assessed using three main concepts: social networks (Study 1), social inclusion (Study 2), and capabilities (Study 3). No significant associations between the duration of the CTO intervention and social outcomes at follow-up were found. The association between involuntary hospitalisation and social outcomes was also tested but no significant associations were found. Because the field of social outcome measurement is relatively undeveloped, a further aim was to contribute to the validation and testing of two recently developed instruments: the Social and Community Opportunities Profile (SCOPE) (Study 4) and the Oxford Capability Questionnaire for Mental Health (OxCAP-MH) (Study 5). The SCOPE performed well overall as a measure of social inclusion but questions were raised about its feasibility (length) and the reliability of one of its sub-scales. The OxCAP-MH demonstrated good psychometric properties (reliability and validity) and represents a promising new multi-dimensional patient-reported outcome measure for use in mental health research. </p