Gerald W. Thomas was raised in Small, Idaho, and attended the University of Idaho as an undergraduate. During World War II he served in the U.S. Navy as one of the pilots of Torpedo Squadron Four. After the war he was employed by the U.S. Soil Conservation Service and the U.S. Forest Service in Idaho.

In 1950, Thomas attended graduate school at Texas A & M University where he later held teaching and research positions. Thomas served as the Dean of Agriculture at Texas Tech University for twelve years. In 1970, he came to New Mexico State University, Las Cruces, where he served as president until his retirement in 1984. In 1976, Thomas was appointed by President Gerald Ford to the Board for International Food and Agricultural Development, U.S. Agency for International Development. Thomas served in this capacity until 1979.

Thomas has authored many books and professional publications and organized the NMSU Pioneers.