The purpose of this white paper is to discuss how descriptive statistics and basic analysis of the daily activities of jails can support safety and help measure and improve performance. It is organized in three parts. Part 1 provides a short overview of the role of jail analysis. Part 2 examines the fundamentals of collecting information from offender management systems and other information systems and proposes a set of key data elements essential for conducting jail analysis. Part 3 describes representative questions and contexts that jail analysts may encounter in practice and discusses ways analysts can generate insights about practice and performance. Collecting and analyzing data can immediately benefit jails. Furthermore, consistent data collection and analysis over time allows jails to derive deeper insights into their operations and provides greater opportunities for improving practices, performance, and outcomes. The paper’s author, Reena Chakraborty, Ph.D., has served as chief of strategic planning and analysis for the DC Department of Corrections since 2012. She also serves as a practitioner in residence at the National Institute of Justice.