Mariel Hemingway was 13 in Lipstick when she played the character 'Kathy McCormick'.
That was over 48 years ago in 1976.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 62, and has starred in 54 movies in total, 53 of those since Lipstick was released.
In Lipstick, I think Mariel Hemingway looks: