Ashley Williams recalls her first exposure to acting. "My sister used to direct us in plays in our house in Rye, N.Y.," she says. "We would get up in front of dinner guests and put on a show." Fifteen years later the two have graduated from dinner theater to prime-time TV. Ashley, 24, costars in NBC's Good Morning, Miami as Dylan Messinger, the sexy-yet-perky hairdresser for an a.m. talk show. And her onetime director Kimberly Williams, 31, plays Jim Belushi's sister-in-law on ABC's According to Jim.

Living just blocks away from Ashley in L.A., Kimberly says she gives big-sisterly advice "only when Ashley asks for it. I try to give her perspective. Sometimes it seems like the world revolves around Hollywood." For Ashley it's a world apart from Rye, where she, Kimberly and brother Jay, now 29 and a firefighter, were raised by their parents, Gurney, 61, a freelance writer, and Linda, 59, a fund-raiser. After juggling high school with a two-season stint as a teen vixen on As the World Turns, Williams earned a B.A. in theater arts from Boston University in 2001.

Last January Kimberly lured her to L.A., where Ashley nailed her first audition—for Miami. "Her allure," says costar Mark Feuerstein, "is that she combines innocence and knowledge." Still, the unattached actress isn't exactly exploiting her celeb status: Her social life, she says, is limited to her Sunday ritual: "eating my sister's apple chicken, watching Alias and playing Scatter-gories. That's all I need."