After graduating from the Ethical Culture School, Marshall spent a year at Columbia University. In 1920, he transferred to the New York State College of Forestry at Syracuse University. Marshall had decided in his teens that he wanted to be a forester, writing then about his love of "the woods and solitude;" he wrote that he "should hate to spend the greater part of my lifetime in a stuffy office or in a crowded city". For a while he was unhappy and withdrawn at Syracuse. But, he succeeded academically and was known for his individuality. As one classmate put it, Marshall was "always doing something no one else would ever think of doing. He was constantly rating things—the Adirondack peaks, his best days with George, and dozens of others." Marshall became a member of Alpha Xi Sigma, the forestry college's honor society. He ran on the Syracuse University freshman track team and participated in both junior varsity lacrosse and cross country running.