studied at the Massachusetts Institute of Technology and the École des Beaux-Arts, Paris. He was of great importance in the evolution of modern architecture in the United States. His dominating principle, demonstrated in his writings and in his executed buildings, was that outward form should faithfully express the function beneath. This doctrine, the accepted and guiding one of modern architecture throughout the world, gained for Sullivan, however, few contemporary adherents. In the face of the powerful revival of traditional classicism in the final years of the 19th cent., little interest was focused on Sullivan's plea for the establishment of an architecture that should be functional and also truly American.
Sullivan was employed in the Chicago office of William Le Baron Jenney, designer of the first steel-skeleton skyscraper, and later entered the office of Dankmar Adler, where he became chief draftsman and in 1880 was made a member of the firm. Adler and Sullivan rapidly became prominent. In Sullivan's Wainwright Building in St. Louis (1890) a tall steel-frame building was so designed as not to belie the structural skeleton. His Transportation Building at the World's Columbian Exposition, Chicago (1893), now demolished, shared nothing of the traditional classicism dominating the rest of the fair, and has become renowned for its originality and for heralding a new viewpoint.
Sullivan in 1901 began to advocate a more imaginative as well as functional expression of architecture in his essays, collected as Kindergarten Chats (1918; ed. by Isabella Athey, 1947). Sullivan's works all bore his stamp in the highly individual ornament that he had built up into a complete style, now identified with his name. The Autobiography of an Idea (1924), which he wrote in his last years, contains the philosophy of his life and work. His executed designs include the Auditorium Building, the Gage Building, the Stock Exchange Building, and the structure that now houses the Carson Pirie Scott department store, all in Chicago; the Guaranty Building, Buffalo, N.Y.; a series of brilliantly designed small banks, above all the National Farmers Bank in Owatonna, Minn. (1906–8); and a number of memorials, including the Getty Tomb in Chicago. Sullivan's pupils and followers include Claude Bragdon and Frank Lloyd Wright.