PROVISION OF SERVICES TO PEOPLE WITH MENTAL ILLNESSES: Edited by Giovanni de Girolamo and Thomas BeckerForty-five years later: the challenge of optimizing assertive community treatmentThorning, Hellea,b; Dixon, Lisac,dAuthor Information aClinical Professor of Psychiatric Social Work (in Psychiatry), Columbia University Research Scientist & Director, ACT Institute bACT Institute, Center for Practice Innovations (CPI), New York State Psychiatric Institute (NYSPI) at Columbia University, Division of Behavioral Health Services and Policy Research cEdna L. Edison Professor of Psychiatry, New York State Psychiatric Institute, Columbia University Vagelos College of Physicians and Surgeons dDivision of Behavioral Health Services and Policy Research and Center for Practice Innovations, New York, New York, USA Correspondence to Helle Thorning, PhD, MS, LCSW, ACT Institute, Center for Practice Innovations (CPI), New York State Psychiatric Institute (NYSPI) at Columbia University, Division of Behavioral Health Services and Policy Research, Room 2709, Box 100, 1051 Riverside Drive, New York, NY 10032, USA. Tel: +1 646 774 8550; e-mail: email@example.com Current Opinion in Psychiatry: July 2020 - Volume 33 - Issue 4 - p 397-406 doi: 10.1097/YCO.0000000000000615 Buy Metrics Abstract Purpose of review: Assertive Community Treatment is an established evidenced based practice that provides intensive community treatment for individuals with severe mental illness with recurrent hospitalizations and/or homelessness. Emerging evidence indicates limitations in its implementation in terms of to the original ACT model and its current relevance. Recent findings: Findings from recent studies (2018–2020) reveals challenges with implementation centered around basic implementation activities, such as changes in the psychosocial context of individuals with SMI, clinicians’ abilities to demonstrate competencies with new practices, and ongoing evolution of mental health systems of care worldwide. Intermediary and purveyor organizations (IPO) can provide the infrastructure to support the spread of EBPs while addressing challenges and opportunities. Thus, implementation of ACT can be accomplished when employing a rigorous framework and infrastructure that can synthesize and translate science relevant for practice. Summary The relevance of ACT depends on its implementation that is responsive to change. An implementation science-informed approach is key to providing ACT to individuals in the critical space between the hospital and community. With this approach, we can optimize ACT as a service delivery vehicle by careful analysis of how best to furnish and evaluate the latest, most effective and efficient treatments, rehabilitation and support services. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.