Shepard graduated from the U.S. Naval Academy, Annapolis, Md., in 1944 and served in the Pacific during World War II. He became a naval test pilot, and in 1958 he graduated from the Naval War College, Newport, R.I. In 1959 he became one of the original seven astronauts chosen for the U.S. Mercury program by the National Aeronautics and Space Administration (NASA).

On May 5, 1961, Shepard made a 15-minute suborbital flight in the Freedom 7 spacecraft, which reached an altitude of 115 miles (185 km). The flight came 23 days after Major Yury Gagarin of the Soviet Union became the first man to orbit the Earth.

Shepard commanded the Apollo (Apollo program) 14 flight (Jan. 31–Feb. 9, 1971; with Stuart A. Roosa and Edgar D. Mitchell), which involved the first landing in the lunar highlands. Shepard headed NASA's astronaut office from 1963 to 1969 and then from 1971 to 1974, when he retired from the Navy and the space program to undertake a career in private business in Texas.