Harold Clayton Urey was born on April 29, 1893, in Walkerton, Indiana, to Rev. Samuel Clayton Urey and Cora Rebecca Reinoehl. After completing his early education in rural schools, Urey earned his graduation in 1911. He taught for three years in country schools before entering the University of Montana in 1914, receiving his Bachelor of Science in Zoology in 1917. Later he spent two years as a research chemist before returning to Montana as an instructor in Chemistry. In 1921, he enrolled at the University of California to work under Professor Lewis, and he received his PhD in Chemistry in 1923.