Mental Health Triage (MHT) tools may be defined as any clinician administered scale that specifies psychiatric signs or symptoms, proposes a corresponding service response, and determines priority categories based on the level of perceived acuity. Multiple MHT tools are used across different jurisdictions and care settings. This article summarizes the literature on MHT tools, describes the available tools and the supportive evidence, evaluates the impact and clinical applications, and compares their strengths and weaknesses. This review utilized a systematic review process to identify articles examining MHT tools. Several benefits of using MHT tools are described; however, in general, the supportive evidence for their use is lacking. A modified Australasian Triage Scale has the strongest evidence base for use in emergency settings; however, further data are needed to establish improved outcomes. There is limited evidence for the use of MHT tools in ambulatory or primary care settings. No evidence was found supporting any one tool as effective in guiding service responses across the entire clinical spectrum. Future research could focus on developing and evaluating MHT tools that service all levels of illness presentation. Additionally, more robust studies are required to support the use of MHT tools in emergency settings. Finally, there is an impetus for the development and evaluation of MHT tools in ambulatory, community, and primary care settings.