Sara Gilbert has signed on as a series regular for CBS' The Big Bang Theory.

According to Variety, Gilbert guest starred on three segments in the Warner Bros. TV comedy's first season. She'll continue in the role of egghead Leslie Winkle, a love interest to Johnny Galecki's Leonard, a fellow egghead who's trying to come out of his shell with women. Gilbert and Galecki previously co-starred as sweethearts on the later seasons of ABC's Roseanne.

The Big Bang Theory, co-created and exec produced by Chuck Lorre and Bill Prady, starts its second season Sept. 22.