This paper reviews empirical evidence showing that the structures of the social networks of mentally ill clients influence both their well-being and their use of mental health services. Network interventions that might help clients better address network-related problems, and might help their families improve relationships and prevent caretaker's burn-out are presented. A case illustration will demonstrate how practitioners can assess a client's social network, involve the client's family in treatment, evaluate that treatment, and select tailored interventions. This case will emphasize both how practitioners can help a client restructure her network, and the complementary roles of formal and informal networks. The author shows practitioners how to match clients' initial network structures to interventions and desired outcomes. Practitioners can thus help clients modify their social networks, increase the use of preventive services, and improve their well-being.