Few services for persons with serious mental illness have been as supported by evidence as assertive community treatment (ACT). As the study by Horvitz-Lennon and colleagues (1) in this issue shows, ACT increased access to outpatient services among clients from diverse ethnic backgrounds, building upon its proven ability to reduce hospitalizations.

Although these findings are a sophisticated contribution to the ACT literature, they raise a few questions as ACT enters its fourth decade. First, why isn't ACT more common? As of 2009, a total of 38 states had adopted ACT, but only about 2.3% of mental health clients were being served by ACT (about 60,000 persons nationwide) (2). Although the large number of mental health clients with less severe diagnoses partly account for this low rate, it is hard to imagine that almost 98% of users of public mental health care are inappropriate candidates for ACT services.

Given its intensity—smaller caseloads, 24-7 open-ended commitment, and ongoing fidelity monitoring—implementing ACT may seem daunting and close to an all-or-nothing proposition (3). This leads to a second question: how does ACT fit the varying needs of mental health clients? Its effectiveness is well-established for clients with more severe disabilities (3); however, ACT seems less equipped to serve clients whose needs are episodic or sporadic (4) and those who are well on their way to mental health recovery (5). ACT's step-down capacity—that is, the ability of ACT teams to provide a less intensive approach, linking clients to specific services as needed—has received some attention but remains poorly understood and operationalized (5). To make matters more complicated, ACT sometimes needs to be stepped up—that is, expanded to address comorbid problems such as poor health and substance abuse. ACT has been described as a suitable platform to deliver other evidence-based practices, such as integrated dual disorders treatment (6), although such practices require that traditional ACT services be repurposed. For now, the ways in which “ACT step-down” or “ACT step-up” affects fidelity—and, more important, client outcomes—remain to be seen.

Recent legal changes bring renewed urgency to this discussion. In October 2010, the U.S. Department of Justice entered into a comprehensive settlement agreement with the State of Georgia that will transform its mental health system in order to comply with the Olmstead decision (7). This agreement, designed to serve as a road map for other states, introduces once again (four decades later) the challenges of deinstitutionalization and community support. ACT's formidable potential in the wake of the Georgia settlement awaits resolution of some pertinent issues. For example, reimbursement policies do not easily accommodate time spent traveling to and from clients' residences, either in rural settings or in urban areas that lack reliable public transportation and that are subject to traffic delays. Although telepsychiatry may help fill the gap, it would require significant modifications (8) that could undermine the therapeutic relationships engendered by ACT's intensity of service. Research on ACT can keep pace by examining how it might be modified to meet exigencies emerging from the diversity of clients and service settings and from episodic or declining trajectories of need across the life span.

ACT has endured in large part because of its premise of literally going where the client is. Whether stepped up or down, ACT's central principles—being proactive rather than reactive, integrated rather than fragmented, continuous rather than disjointed—have much to offer. Indeed, ACT can be seen as a gold standard (9), both in its evidence base and in its adaptability in the era of recovery (5).