Captain Willliam Shepherd graduated from the US Naval Academy and was commissioned in the US Navy in 1971. He completed Basic Underwater Demolition/SEAL training in 1972 and was subsequently assigned to SEAL Team ONE, spending two years as a platoon commander in Korea, the Philippines and Alaska.

William Shepherd attended the Navy's Naval Construction and Engineering program at MIT, graduating in 1978 with the degrees of Ocean Engineer and Master of Science in Mechanical Engineering. He returned to the Special Warfare community and was deployed as a platoon commander operations in El Salvador, Honduras, Grenada, and Beirut. NASA selected him in 1984 as an Astronaut Candidate.

After a year of astronaut training at Johnson Space Center in Houston, William Shepherd was assigned to work pad "closeout" operations for Space Shuttle launches at the Kennedy Space Center. He was involved in the underwater search and salvage of the Space Shuttle Challenger in 1986. Shepherd flew three Shuttle missions as a Mission Specialist and flight engineer:  STS 27 which carried a Department of  Defense payload, STS 41 that launched the solar probe "Ulysses", and STS 52 which carried the LAGEOS research satellite to orbit.

In 1993, William Shepherd was assigned as the Program Manager for the International Space Station, and in 1996, he was selected to form a crew with Russian Cosmonauts Col. Yuri Gidzenko and Sergei Krikalev, and command the first crew to the new station. After 5 years of training in Moscow and Houston, the "Expedition One" crew launched in October 2000 and began permanent human operations aboard the 100-ton Space Station "Alpha" complex. The crew returned to Earth in March 2001 after 141 days in space.

Captain William Shepherd is currently assigned to the staff of Commander, Naval Special Warfare Command, to assist with the development of new capabilities and programs for the SEALs and Special Boat sailors of tomorrow. He retired from active duty in Jan. 2002 and remains on staff as a civilian engineer.

Shepherd is married to the former Beth Stringham of Houston Texas, the chief strength and conditioning specialist for the Astronaut Office at NASA's Johnson Space Center.