Participation is often the comprehensive objective of treatment but also an indication of the extent to which the process of occupational therapy is client-centred. The purpose of this study was to explore levels of participation during occupational therapy among clients in the area of mental health from the occupational therapists' perspectives. Additionally the authors sought to identify factors that might hinder client participation. Postal questionnaires were sent out to 670 Swedish occupational therapists working with persons with mental illness and learning disabilities. The questionnaire required therapists to rate clients' levels of participation during occupational therapy. Findings indicated that the most common level of participation for the clients was interdependent, meaning that problems, goals, and plans were identified jointly and collaboratively with the occupational therapist. However, more than 20% of the clients were described as being dependent. Almost 90% of the occupational therapists rated client participation in therapy to be very important and nearly 70% claimed that client participation in general needed to be increased. Occupational therapists rated the primary barriers to participation as being clients' inability to participate and organizational and financial problems. Implications of these findings for education in client-centred practice approaches are discussed.