The study examined the availability and characteristics of assertive community treatment (ACT) programs across mental health treatment facilities in the United States.Methods: Prevalence and correlates of facilities that reported offering ACT, broadly defined as intensive community services for serious mental illness provided by multidisciplinary teams in the clients' natural settings and including both ACT and "ACT-like" programs, were examined by using data from the National Mental Health Services Survey. Availability of services essential to the ACT model in these facilities was also examined.Results: Of the 12,826 surveyed facilities, 13.4% reported offering ACT, with significant variability among states. Of the facilities with ACT, 19.2% reported offering all core ACT services. Few facilities offered peer support, employment, and housing services. Compared with programs at facilities that did not offer all core ACT services, facilities with ACT programs that offered these services had higher odds of being publicly owned (odds ratio [OR]=2.12, 95% confidence interval [CI]=1.64-2.74) and of receiving federal (OR=3.60, CI=2.17-5.98) or grant funding (OR=1.87, CI=1.45-2.41). Facilities with ACT that offered all core services also had higher odds of offering other services important to individuals with serious mental disorders.Conclusions: Substantial differences existed in availability of ACT and ACT-like programs among states, with evidence of a large unmet need overall, even when a very broad and inclusive definition of ACT was used. Few ACT programs offered all core services. Legislative, administrative, and funding differences may explain some of the variability.