Born in Brookline, Massachusetts, Codman graduated from the Massachusetts Institute of Technology in 1884 and immediately went to work for Frederick Law Olmsted, Sr. During this initial two-year apprenticeship, Codman worked on plans for Harvard’s Arnold Arboretum, among other projects. In 1887, he undertook a study-tour of parks, gardens, and nurseries throughout England, France, Germany, and Italy, and then spent a year in Paris apprenticed to the horticulturalist and landscape gardener Édouard André. Codman returned to the United States and became a partner in F.L. Olmsted & Company in 1889. That same year, he published the article “The National School of Horticulture at Versailles” in the journal Garden and Forest. He was directly involved in the design and construction of South Park and Cazenovia Park in Buffalo, and he worked with Olmsted on the design of Jackson Park and the Midway Plaisance in Chicago. Codman also assisted in the landscape design for the World’s Columbian Exposition of 1893, winning the admiration of Danial Burnham, who praised his “knowledge of formal settings” and his “instincts.” While working on the Exposition, Codman underwent an appendectomy, contracting an infection from which he did not recover. He died at the age of 29. After Codman’s death, Charles Eliot joined the Olmsted firm, which was renamed Olmsted, Olmsted & Eliot.