This essay presents an overview of what is known about prosecution systems at the State level in the United States and across different countries. The essay summarizes structural, normative, and policy characteristics and differences across national prosecution systems, discusses the effects of these differences, and discusses the explanations for why these differences occur. The differences in prosecutorial systems can be divided into two types: foundational differences between systems and normative differences that influence the day-to-day operations and decisions of each system. Foundational differences include adversarial and inquisitorial systems; the legality and expediency principles; and democratic accountability. Normative differences deal with structural location - where the prosecutors are located within the judicial or executive branch of the government. Differences in prosecutorial systems also occur in the selection, recruitment, and training of prosecutors. These differences are then discussed as they affect diversion, charging, bargaining, and sentencing. The final section of the essay examines future directions for research on the effects of differences in prosecutorial systems. References