After graduation she joined the National Ballet of Canada, where she became Principal Dancer in 1971, dancing central roles in a wide array of ballets, eventually becoming the most well-known dancer in Canada.
In 1973 she won silver in the women's competition and another silver for Best pas de Deux (with Frank Augustyn) at the second International Ballet Competition.
In the late 1970s she stopped dancing for a period, but in 1980 resumed dancing with the National Ballet of Canada, where she stayed for 15 years, retiring from dancing in 1997 (one source says 1994).
In 1976 she became an Officer of the Order of Canada and in 1991 became a Companion of the Order of Canada and she has honorary degrees from the University of Toronto, York University, McMaster University, Trent University, and the University of British Columbia. In May of 1998, the French Government named her an Officer of the Order of Arts and Letters.
She's the president of the Dancer's Transition Centre and in 1992 she received the Performing Arts Award. In 1996 she received the Cartier Lifetime Achievement Award, the first Canadian to do so and in 1997 she received the National Arts Centre Award.
She's worked as a guest artist with Roland Petit's Le Ballet National de Marseilles, the Bolshoi Ballet, the London Festival Ballet, The Paris Opera Ballet, Hamburg Ballet, Vienna State Opera Ballet, and Eliot Feld Ballet.
In 1998, Ms. Kain returned to the National Ballet of Canada, now as part of the senior management team.