OBJECTIVE People with severe mental illnesses experience difficulty finding and maintaining employment, even if they are offered psychiatric vocational rehabilitation services. When service recipients are able to apply more effective illness self-management strategies, vocational rehabilitation outcomes improve. To assess the use of these strategies, the Illness Self-Management assessment instrument for Psychiatric Vocational Rehabilitation (ISM-PVR) was developed. METHODS Experts were consulted to design the ISM-PVR instrument which was then tested by 8 vocational rehabilitation workers and 26 of their service recipients. RESULTS This study indicated sufficient internal consistency of the ISM-PVR self-report questionnaire, especially for the subscales assessing goal related self-efficacy, perceived illness-related barriers, and four of the eight coping scales. The number of self-reported illness barriers was associated with a higher number of reported work-related coping strategies. The ISM-PVR aided the identification of specific mental illness-related barriers perceived by the service recipients. The instrument also facilitated obtaining information on individual self-management strategies that clients employed to overcome such barriers or make them manageable. CONCLUSIONS The application of the ISM-PVR in vocational rehabilitation practice warrants further research. The study suggests that this instrument is a useful add-on to existing vocational assessment and provides insight in self-management strategies that people use, and that may help those people and their job coaches make more effective vocational plans.