O'Toole's first major film role was as a jaded beauty pageant contestant in the 1975 satire Smile; she got the role after doing an impression of a "dead cockroach" at the audition. She also appeared as Robby Benson's character's tutor/girlfriend in the college basketball story One on One in 1977. She co-starred opposite Gary Busey in the 1980 film Foolin' Around. In 1981, she starred in the HBO onstage production of Vanities, as well as in the TV movie Stand By Your Man, which detailed the life of country music legend Tammy Wynette. Later on in 1982, she appeared briefly as Nick Nolte's girlfriend in 48 Hours. That same year, she played Alice Perrin in Cat People, and then in 1983 she played Lana Lang (love interest to Clark Kent/Superman), and single mother of Ricky in Superman III. In 1985, she co-starred with Barry Manilow in the CBS television movie Copacabana playing Lola La Mar to Manilow's Tony Starr. Also in 1985, she had a starring role as Ms. Edmunds in the original Bridge to Terabithia, and appeared in the TV adaptation of Strong Medicine the following year. In 1987's Cross My Heart, a romantic comedy, O'Toole had a leading role opposite Martin Short.