Kaley Cuoco, who recently lived under "8 Simple Rules," will learn about the power of three in the coming TV season.

Cuoco has signed on as a regular in The WB's "Charmed" for 2005-06, her first regular role in a drama series. She'll play a young witch being trained by the Charmed ones, according to The Hollywood Reporter.

That "Charmed" will be back for an eighth season was something of a surprise at the May upfronts; the show has suffered ratings declines in the past couple of seasons, and there was speculation that The WB would cancel it. It survived, however, and will continue to anchor the network's Sunday schedule.

In addition to Cuoco, the show will also feature Sugar Ray singer/"Extra" anchor Mark McGrath in multiple episodes this season.

Cuoco played the shallow, spoiled Bridget Hennessy on "8 Simple Rules," which ABC cancelled this spring after three seasons. She starred in the ABC Family movie "Crimes of Fashion" and appeared in the NBC miniseries "10.5" last year. Her credits also include playing "Brady Bunch" star Maureen McCormick in the 2000 NBC movie "Growing Up Brady."