Harry Mills Walcott received his earliest formal artistic training in the schools of the National Academy, where in 1890, he commenced three years in the antique class, and four years in the life class. In 1891, Walcott began three years of study in the painting class. Evidently, Walcott was an extremely capable student. On May 8, 1894 at the end of his studies, the Academy awarded Walcott with the Havemeyer Travelling Scholarship to study abroad.
After arriving in Paris during the fall of 1895, Walcott enrolled for two years at the Academie Julian, under Jean-Joseph Benjamin- Constant and Jean-Paul Laurens. He wrote he was working there "from eight A.M. to five P.M. and doing a little at night also" (Letter, Walcott to NAD, November 12, 1895). In the spring of 1896, he visited the town of Barbizon and the forest of Fontainebleau. Walcott sketched and painted in Etaples that summer, rendering his landscapes en plein air and hiring the local fisherman as models for his figure studies. He made a brief trip to England, returning to Etaples. Before he returned to the United States in 1898, Walcott received an honorable mention at the Paris Salon.
After his return, Walcott was appointed summer instructor of painting at the Portland Academy in Oregon. He also executed numerous magazine illustrations for periodicals such as Century, Scribner's, and McClure's. In 1905, he married the painter Anabel Havens, whom he had met in Paris. The couple spent many years near La Jolla, California, although, during the 1940s, they also resided in Rutherford, New Jersey.
