Yeardley Smith was 19 in Heaven Help Us when she played the character 'Cathleen'.
That was over 39 years ago in 1985.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 59, and has starred in 41 movies in total, 38 of those since Heaven Help Us was released.
In Heaven Help Us, I think Yeardley Smith looks: