Put it this way: Father Knows Best's teenage Princess has moved into the Jane Wyatt role. From 1954 to 1963 Elinor Donahue was Betty, the wholesome, willowy older daughter of those proud TV parents Jim and Margaret Anderson. Today Donahue, 50, is the wholesome mother in the Fox Network's Saturday night spy spoof, The New Adventures of Beans Baxter, happily and obliviously running a household while her teenage son works as an undercover intelligence agent. "Mrs. Baxter is a glorified, updated '50s mother," says Donahue, in the living room of her North Hollywood home, "a very upbeat person who wears pastel colors but isn't that sweet, really." Actually, she's a mom with a ditsy, absurdist edge, perfect for the '80s. In a typical scene, Beans (Jonathan Ward, 17) tells her that he's just found a Russian spy sitting in an upstairs bedroom, playing the tuba in the nude. Busy baking cookies, Mrs. Baxter's only response is, "I wondered what that noise was."

Donahue is one of the few actresses with a prayer of pulling that off. As sweet and warm as a morning Danish and coffee, she has always projected a comforting stability. She was an ideal casting choice by Beans Baxter's creator, the self-nicknamed wacko wunderkind Savage Steve Holland. Intending Beans Baxter to be what he calls "a Leave It to Beaver with guns," Holland needed a TV mother who could anchor the show's freestyle fantasy. He found her in apple-pie Elinor. "She's the perfect mom," says Holland, 27. "She's everybody's mom."

But of course it isn't that simple.

Since leaving prime time 24 years ago Father Knows Best has become notorious for the tribulations of its cast. Robert Young, the titular dad, survived extended bouts with alcoholism and depression. Billy Gray and Lauren Chapin, who played the younger siblings, Bud and Kathy, each developed drug problems. Donahue had her own misadventures. Born in Tacoma, Wash., Elinor had been America's Princess for two years before she rebelled at 19. "I decided I wanted to be grown up," she says. "And how do you do that? You go off and get married and have a baby and you don't have any more problems." Her choice as a husband, Dick Smith, was a sound man for Father Knows Best. Donahue and Smith had a son, Brian, and split within two years. "There was nothing the matter with Dick or me," says Elinor. "We got married for all the wrong reasons. It wasn't meant to be."

In 1961 she married her present husband, Harry Ackerman, a man 25 years her senior who would go on to produce such series as The Flying Nun, Bewitched and, currently, The New Gidget. Initially Donahue's second marriage seemed no more likely to last than her first. Besides working, she was trying to raise her own son and live on and off with Harry's two teenage children, Steve and Susan, from a previous marriage. The pressure was intense. "I was just an insecure 23-year-old," says Donahue. "I didn't know how I was going to survive. I kept thinking, 'I'm going to end up in a home, or maybe I'll just sit in a cell somewhere.' I even thought about going to the Trailways bus terminal, asking the man, 'How far will this bus take me?' and becoming a waitress somewhere."

Fortunately Trailways never got her business. Donahue stuck it out and learned to play mom in real life. She credits Harry for mooring the family ("He's the saint, I'm the hysteric"). The couple has successfully brought up the three kids they brought to the marriage, plus three more they've had together. Susan, 42, is the mother of three. Steve, 39, is a film technician. Brian, 30, is a caterer. Peter, 25, is an actor and production assistant. James, 22, is a sales rep. Chris, 19, has given up heavy-metal drumming and is studying for the ministry. In sum, a typical American family.

As an actress, Donahue has shown equal endurance. She was featured on The Andy Griffith Show and The Odd Couple and appeared as nurse Kate Honeycutt on the daytime soap Days of Our Lives from 1983 to 1986. Donahue and the rest of the Father Knows Best cast, who reunited for a 1977 TV movie, hope to regroup for another sequel in the near future. Though the original series is still in reruns, Elinor never watches it. "I just don't think to put it on," she says. "It was a product of its time, a kind of moment in history. It wasn't meant as a treatise on how family life should be."

But if she doesn't watch the show, she hasn't forgotten it either. On Donahue's bed is a gently ironic gift from her husband, a ruffled pillow inscribed, "It's not easy being a Princess." Maybe, in this case, Father does know best, after all.