PurposeThe purpose of this paper is to provide a comprehensive literature review of prior empirical studies that have examined early intervention (EI) systems or programs in policing.Design/methodology/approachA systematic literature search of various government and academic databases (e.g. Emerald, Google Scholar, National Criminal Justice Reference Service (NCJRS), Sage, Taylor & Francis and Wiley) was conducted.FindingsThis systematic review identified eight EI studies that matched the selection criteria. Of these, two are multiagency studies and six are individual agency studies. Findings across studies are generally positive but overall relatively inconsistent with regard to EI systems' effectiveness.Practical implicationsPolice agencies benefit in identifying and addressing at-risk officers to ensure police accountability and officer safety, health and wellness. This research is invaluable for optimizing how EI systems can use agency data for such predictions.Originality/valueThis state-of-the-art review on EI systems in policing is the first of its kind. EI systems have been implemented by many police agencies, yet a limited number of empirical studies have been conducted. This systematic review will be useful for researchers who wish to further explore how EI systems are utilized and whether EI systems are successful/effective.