Mental health professionals are expected to stimulate the participation of service users with serious mental illness. This not only changes what is expected from service users and professionals, it also changes the values underlying their relationship. The value of autonomy becomes more important as a result. This raises potential ethical dilemmas. This paper reports the findings of a thematic synthesis of 28 papers on the views of service users, professionals and family members on the care relationship in inpatient, outpatient and community services for people with serious mental illness. It puts forward various perspectives on participation of service users, foregrounding differing values, which in turn can lead to ethical dilemmas for professionals. The key implications for mental health professionals and future research are discussed.