The High Energy Physics research program explores the most fundamental questions about the nature of the universe. The Office of High Energy Physics supports a program focused on three frontiers of scientific discovery. At the Energy Frontier, powerful accelerators investigate the constituents and architecture of the universe. At the Intensity Frontier, astronomically large amounts of particles and highly sensitive detectors offer a second, unique pathway to investigate rare or difficult to detect events in nature. At the Cosmic Frontier, natural sources of particles from space reveal the nature of the universe. Together these three interrelated discovery frontiers create a complete picture, advancing Department of Energy missions through the development of key cutting-edge technologies and the training of future generations of researchers. To explore these frontiers, the Office of High Energy Physics research program is composed of five subprograms that are organized around the tools and facilities they employ and the knowledge and technology they develop.