After graduating from LaGuardia when she was seventeen years old she took a class at
Alvin Ailey American Dance Theater. She was noticed by
Alvin Ailey and he invited her to join the professional company. She toured with Alvin Ailey American Dance Theater as a modern dancer, but kept up her ballet and pointe training, upon Ailey's insistence. Ailey encouraged Stevenson to audition for the ballet company at
Radio City Music Hall. She auditioned and was told to work on her
fouettés and come back in two weeks. She auditioned again and was accepted, joining the Radio City Music Hall Ballet Company as its first African-American dancer. Due to her race, original roles were created for her as there weren't many roles within classical ballets that were traditionally for black dancers. Stevenson left Radio City Music Hall and auditioned to be a student at the
School of American Ballet with hopes of joining the
New York City Ballet. She was accepted and received a scholarship to study at the school. She was a student at the School of American Ballet for two years but was not offered a position in the company, despite many of her classmates joining. She asked
George Balanchine, director of the School of American Ballet and New York City Ballet, what her prospects were for dancing professionally. Balanchine expressed that although
Arthur Mitchell, an African-American male dancer, was dancing with New York City Ballet, the company was not ready to have a woman of color, stating that a black woman would "break the corps line." Stevenson later auditioned for
Frederic Franklin's
National Ballet of Washington and was accepted as a member of the corps de ballet. She was the only African-American dancer in the company at the time she joined. After dancing in the corps at the National Ballet of Washington for a few years, she was contacted by Arthur Mitchell, who had retired from New York City Ballet and founded
Dance Theatre of Harlem, to join his company. She joined Dance Theatre of Harlem as a founding member and was the company's first principal dancer. She danced many principal roles at Dance Theatre of Harlem, including one of the lead roles in Balanchine's
Concerto Barocco. She toured with the company and even performed at
Jacob's Pillow Dance. While at Dance Theatre of Harlem, Stevenson wore brown tights over her pink tights, paving the way for ballet dancers of color to start wearing brown tights and pointe shoes, breaking from the tradition of pink tights and shoes. ==Conversion and retirement==