Over the last 30 years, the Department of Justice (DOJ) has used the pattern-or-practice initiative to implement police reform in maligned law enforcement agencies. Despite the longevity of the program, there is limited empirical evidence that assesses the effectiveness of the initiative, and what evidence exists shows mixed results. This paper advances prior scholarship in this area by considering what is known about the program, outlining the implied theory of the DOJ’s efforts, lamenting the lack of evaluation evidence, and prescribing a modern research agenda for this topic area.