This CMB-OC is a three-year project that will develop and assess a method of adding psycho-social support services provided by social workers to current Methadone Maintenance Treatment (MMT) programs with the goal of decreasing the high drop-out rates from these programs. Dropout rates, abstinence (compliance) rates, and psychological symptoms over a six-month period will be compared between two groups: 200 clients who receive standard MMT at two randomly selected MMT centers in Guangzhou, and 200 clients who receive standard MMT plus adjunctive psycho-social support at two other MMT centers.