William Cochran is a Senior Research Scientist with McDonald Observatory. He received his B.S. degree in physics from Duke University, and his Ph.D. in astrophysics from Princeton. He came to the University of Texas as a PostDoc in 1976, and has been here ever since. He started his career studying the composition and structure of outer planet atmospheres. His interests then shifted to the detection and characterization of extra-solar planets. In 1989, he and Artie Hatzes started one of the pioneering ground-based radial velocity searches for giant planet companions to nearby stars, using the McDonald Observatory 2.7m Harlan J. Smith Telescope. This search program has grown tremendously, and now also uses the Hobby-Eberly Telescope and the W.M. Keck Observatory as appropriate. Cochran is a Co-Investigator on NASA's Kepler spacecraft mission. Kepler is designed to determine the frequency of terrestrial and larger planets in or near the habitable zone of a wide variety of types of stars by searching for the minute dimming of the star light as a planet transits the star. Cochran's role in Kepler is to use ground-based telescopes to conduct complementary follow-up observations to confirm that the transits seen by Kepler are due to planets and to learn more about the characteristics of the parent stars and planetary systems.