Willard was born on June 3, 1881, in Erie, Pennsylvania. His family relocated to Union City, Michigan, in 1883 and he spent the rest of his early life there. His father and later his high school teachers encouraged his interest in chemistry, which he pursued as an undergraduate at the University of Michigan. He received his A.B. in 1903 and his M.A. in 1905. Meanwhile, he was briefly hired as an instructor of chemistry, but at the encouragement of coworkers he decided to pursue his Ph.D. at Harvard University. He received his Ph.D. in 1909 under the supervision of Theodore William Richards.