This graduate textbook provides a concise, accessible introduction to the Standard Model of particle physics. Theoretical concepts are developed clearly and carefully throughout the book--from the electromagnetic and weak interactions of leptons and quarks to the strong interactions of quarks. Chapters developing the theory are interspersed with chapters describing some of the wealth of experimental data supporting the model. The book assumes only the standard mathematics taught in an undergraduate physics course; more sophisticated mathematical ideas are developed in the text and in appendices. For graduate students in particle physics and physicists working in other fields who are interested in the current understanding of the ultimate constituents of matter, this textbook provides a lucid and up-to-date introduction.