Family involvement in mental health treatment has been shown to improve outcomes for service users. This project used a whole system‐focused action research framework and involved service users, family members and healthcare professionals to develop ways to improve family engagement in an adult inpatient mental health service. Focus groups were conducted with two service users, two family members and four healthcare professionals to discuss their experiences of family involvement and develop initial ideas. A problem‐solving group, involving service users, family members and professionals, was used to develop the solutions. The project identified context‐specific solutions to improve family engagement, which included specific training for professionals working on the inpatient wards, questionnaires to facilitate conversations with families, and sharing information about mental health and the inpatient mental health service with families. These may be helpful for other adult inpatient services.