Mental health system reform oriented toward realizing the transition from “institutionbased medical treatment” to “community-based care” is now taking place in Japan. Although the number of psychiatric beds is slow to decrease, community resources are increasing, and differentiation of those services is the next challenge.
 Assertive Community Treatment（ACT）is a service which provides 24/7 community outreach by a multidisciplinary team to persons with severe mental illness. Currently,some 10 to 15 ACT teams are providing services in Japan ; this number is far from adequate. This is due to the lack of direct funding for ACT in the current mental health system. However, ACT is increasing as a result of combining available funding sources, such as psychiatric home visit nursing and welfare funding. The ACT Network, a voluntary association, was established to disseminate ACT and ensure its quality. Fidelity scales measure faithfulness to the original model. DACTS, a fidelity scale developed in the U.S., is widely used to measure ACT fidelity.
 In Japan,ACT Network implements a Japanese version of fidelity measurement for ACT around Japan. Results of fidelity measurements of 12 ACT teams in 2009 showed that the ACT teams were providing services which adhered more closely to the original model than in the previous year, but problems remained. Some issues, such as increasing care management in services, can be addressed through maturation of ACT teams,but other issues,such as relatively low service density and allocation of employment specialists,cannot be resolved without a funding mechanism. To disseminate ACT and support more people with severe mental illness in the community, it is necessary to build ACT into the community mental health system with sufficient funding, and to monitor its quality using measures such as fidelity scales.