BACKGROUND: There is evidence that insight and social judgements are impaired in schizophrenia. The influence of these factors on the decision to treat compulsorily in schizophrenia is poorly understood. AIMS: To investigate the contribution of insight, social knowledge, and working memory to the determination to treat coercively in schizophrenia. METHOD: Insight rating scale, social knowledge questionnaire and working memory tests were administered to detained patients with schizophrenia. Results were compared with those of a control group of voluntary in-patients with schizophrenia. RESULTS: Detained patients scored worse on insight and social knowledge, yet there was no significant correlation between these scores. There was no significant difference in severity of psychopathology between the experimental and control groups. Results for working memory were inconclusive. CONCLUSION: Insight and social knowledge are significantly, but independently, associated with the determination to treat coercively in schizophrenia. This suggests that insight and social knowledge are distinct skills. The contribution of working memory remains unclear.