Front Matter -- Preface -- Acknowledgments -- Contents -- Executive Summary -- 1 Introduction -- 2 What Is Elementary-Particle Physics? -- 3 Symmetries, Forces, and Particles -- 4 The Past 25 Years: Establishing the Standard Model -- 4 The Past 25 Years: Establishing the Standard Model -- 5 The Physics of the Next Decade -- 6 Accelerators and Detectors: The Tools of Elementary-Particle Physics -- 7 The Role of New Facilities -- 8 Accelerator-Detector Technology and Benefits to Society -- 9 Interactions with and Connections to Other Branches of Physics and Technology -- 10 Elementary-Particle Physics in Today's Society -- 11 Conclusions and Recommendations -- Appendix Glossary, Abbreviations, and Acronyms.