A screening tool for assessing satisfaction with daily occupations among people with mental illness has been devised - the Swedish version of the Satisfaction with Daily Occupations (SDO) instrument - comprising a satisfaction scale and an activity level scale. The aim was to investigate the SDO for content validity, clinical utility, sensitivity to change and discriminant ability. Nine occupational therapists evaluated the content validity of the SDO. Sensitivity to change was assessed on a sample of 36 clients in psychosocial occupational therapy. Discriminant ability was evaluated by comparing four samples: (1) 103 clients with a diagnosis of severe mental illness, (2) 55 clients attending an outpatient mental health clinic, (3) 36 women with a diagnosis of systemic sclerosis and (4) 40 healthy women. The SDO rendered positive ratings regarding content validity, but some rewording of items was indicated as well as clearer instructions. Both the satisfaction scale and the activity level scale were found to be responsive to change. Discriminant ability was shown in that, in particular, the activity level score distinguished the mentally ill participants from the other samples. The SDO was shown to reflect the targeted phenomenon satisfactorily and to be sensitive enough to detect change following an occupational therapy intervention. However, so far only the Swedish version of the SDO has been studied, but an English version is available whose cross-cultural validity should be examined.