In the 1890s, toured as a stage actor with regional companies
Joined the Biograph motion picture studio in 1908, where he was given the opportunity to direct and was so successful that he went on to direct almost all of the hundreds of films that the company produced
Invented editing techniques such as crosscutting, parallel montage, and rapid editing and developed the practice of filming out of sequence
Built a stable of acting talent that launched stars such as Mary Pickford, Mae Marsh, Robert Harron, and Dorothy and Lillian Gish
In 1913, left Biograph, taking his acting ensemble with him, because the studio refused to follow the trend toward multi-reel, feature-length films
The Birth of a Nation (1915), the Civil War epic for which he is best known, was criticized as racist at the same time that it was praised as a masterwork of filmmaking technique, offering almost three hours of affecting performances and impressive battle scenes woven together by rapid-fire editing
Countered The Birth of a Nation with his next picture, Intolerance (1916), which broke new cinematic ground by intercutting four different stories, from four different time periods, to illustrate the history of injustice in the world
In 1919, partnered with Mary Pickford, Douglas Fairbanks, and Charlie Chaplin to found United Artists, where he produced Dream Street (1921), the first American feature with synchronized sound
Sold his share in United Artists after a string of financial failures, but returned to the studio to make 1931's The Struggle, a low-budget drama about alcoholism that bombed and effectively ended his career, becoming the last of the 530-odd films that he directed