This chapter describes the importance and need for interdisciplinary collaboration in forensic settings. It discusses how the evidence-based principles of risk, need, and responsivity (RNR) model can guide interdisciplinary collaboration with justice-involved individuals. The chapter highlights a treatment program for high-risk justice-involved males demonstrating interdisciplinary collaboration and specifically the role of the forensic social worker. Interdisciplinary collaboration is an essential core skill in evidence-based forensic social work practice. Interdisciplinary collaboration can be multidimensional, interactional, and developmental, and the following strategies have been identified as most important in achieving a best practice: preplanning, commitment, communication, strong leadership, understanding the cultures of collaborating agencies, and structural supports and adequate resources for collaboration.