The Knowledge About Schizophrenia Questionnaire (KASQ), a 25-item multiple-choice test, was developed to assess patients' knowledge about their illness and its management. A total of 136 inpatients participated in four studies, including one cross-validation study, to examine the reliability and validity of the KASQ. Reliability was assessed by measuring the test's precision, internal consistency, and stability of scores. Validity was investigated by comparing patients' scores before and after participation in an educational intervention, and by comparing these scores with those of a waiting-list control group. Results indicate that the KASQ has sound psychometric properties and support its use as an outcome measure.