This review, an update of the Particle Data Group's 1969 compilation, provides an updated overview of particle properties, including leptons, mesons, and baryons. The review is organized into several sections, covering introduction, statistics, data retrieval and selection, criteria for resonances, notes on tables, stable particles, mesons, and baryons. It emphasizes the importance of consistent data handling and the use of weighted averages, with detailed procedures for dealing with inconsistent data. The review also includes a discussion of the symbol system used for mesons and baryons, and provides guidelines for interpreting the data card listings. Additionally, it offers procedures for constrained fits and addresses the handling of inconsistent constrained data. The review concludes with acknowledgments and a bibliography.This review, an update of the Particle Data Group's 1969 compilation, provides an updated overview of particle properties, including leptons, mesons, and baryons. The review is organized into several sections, covering introduction, statistics, data retrieval and selection, criteria for resonances, notes on tables, stable particles, mesons, and baryons. It emphasizes the importance of consistent data handling and the use of weighted averages, with detailed procedures for dealing with inconsistent data. The review also includes a discussion of the symbol system used for mesons and baryons, and provides guidelines for interpreting the data card listings. Additionally, it offers procedures for constrained fits and addresses the handling of inconsistent constrained data. The review concludes with acknowledgments and a bibliography.