Despite increasing attention to prosecutors’ significant role in shaping criminal justice outcomes, there is limited research on what prosecutors do. Existing theories of prosecutor discretion were built on observations of the federal courts and felonies, and empirical tests have relied on case-level data from the front (charging) or back (sentencing) ends of the system. As such, we are missing an understanding of precisely what prosecutors do to impact outcomes in the local courts, particularly in the pretrial process. Drawing on three years of embedded research at the Philadelphia District Attorney’s Office, I begin to fill this gap through three studies of prosecutors and pretrial justice. The first two chapters develop a new theory of prosecutorial discretion grounded in ethnographic observations, interviews, and quantitative analyses of misdemeanor cases. I argue that prosecutors in the lower courts primarily function as case managers, coordinating people and handling paperwork. These case management tasks are so critical as to be dispositive in the majority of cases, and case management becomes the central way that prosecutors influence outcomes. In the second chapter, I test this theory by using benchmarking methods to explore how prosecutors’ case management skills map onto case and defendant outcomes. I find that prosecutors who are better case managers have higher conviction rates, but defendants on their caseload are more likely to be rearrested. This highlights a fundamental tension in a prosecutor’s work, where good case management may be opposed to public safety. Finally, in the third chapter, I leverage rare data on failures to appear (FTA) to explore a previously intractable problem in the study of risk assessment tools: the use of bench warrants as a proxy for defendant FTA. I show how FTAs and bench warrants differ systematically by race and class, and how training on bench warrants instead of FTAs compounds these disparities. These results call into question the use of FTA prediction algorithms for bail-setting purposes. Collectively, my findings provide a new understanding of how prosecutors impact outcomes in the lower courts, reshaping the pathways for meaningful criminal justice reform.