The Caltech REU Site program focuses on gravitational radiation and its detection at the Laser-Interferometer Gravitational-wave Observatory (LIGO). It consists mainly of a ten-week summer research program at Caltech and the two LIGO sites in Louisiana and Washington, involving ten undergraduate students from around the U.S. Research projects involve the physics and engineering of the LIGO initial and advanced detectors, data analysis techniques and software, and theoretical studies of astrophysical gravitational-wave sources. These projects typically cover a large number of physics and engineering disciplines, including astrophysics and gravitational physics, and the experimental research deals with metrology, optics, lasers, material science, mechanical systems, controls, and electronics.