With the Ballet Russe de Monte Carlo, where she danced from 1942 to 1950, her repertoire ranged from classics such as Swan Lake, The Nutcracker and Les Sylphides to contemporary works by George Balanchine.
Born in Brooklyn, Boris studied at the Metropolitan Opera Ballet School and danced with the Metropolitan Opera Ballet from 1937 to 1942. She was one of the first students at the School of American Ballet when it opened in 1934. She danced in the New York debut season of the American Ballet in 1935 and with Ballet Caravan, a group focusing on contemporary American choreography, in 1936 and 1937.
Boris left the Ballet Russe at the end of the 1949-50 season and was forced to end her dancing career soon after because of hip problems that necessitated various operations, according to the Times. She turned to teaching and was on the faculty of the University of Washington in Seattle from 1965 to 1983.
She was also a noted choreographer; her Cirque de Deux and Cakewalk are still performed by regional troupes. The latter, a tribute to minstrel shows, was created for New York City Ballet and was warmly received. Other of her dances for City Ballet, such as Bayou and Kaleidoscope (both 1952) and Will o' the Wisp (1953) were less well received, according to the Times. One of her last pieces was Ragtime, set to Scott Joplin and created for the Houston Ballet in 1975.
Boris also studied psychology and therapy at the University of Washington, where she was named an adjunct professor in 1982. She became president and executive director of the Center for Dance Development and Research in Albany, California in 1986, when she also was president of the California chapter of the American Dance Therapy Association.
She married Ballet Russe dancer Frank Hobi, who died in 1967. The cause of her death was cancer, according to the Times.