Annette Funicello, whose girl-next-door beauty never faded for millions of American baby boomers who met her as a Mouseketeer in the 1950s, idolized her through her beach movies of the 1960s and thereafter remembered her voice and smile as pleasures of a simpler time, died April 8 at a hospital in Bakersfield, Calif. She was 70.

Her death, of complications from multiple sclerosis, was announced by the Walt Disney Co. Ms. Funicello had suffered from the degenerative neurological disorder for more than two decades and became a prominent advocate for increased medical research, never flagging in the perky cheer that first endeared her.

In Walt Disney’s entertainment empire, Ms. Funicello was a princess. Although she wasn’t one of the animated fairy-tale heroines — despite having Cinderella’s humility and Snow White’s gentleness — she belonged to the real-life television royalty of “The Mickey Mouse Club.”

(The Mickey Mouse Club continued to generate stars from Mouseketeer ranks in later decades, notably Britney Spears, Christina Aguilera and Justin Timberlake.)

First aired in 1955, the children’s television variety show featured two dozen children known by their first names and bedecked in Mickey Mouse ears who performed in skits and generally provided high-spirited youth-oriented entertainment.

With the word “ANNETTE” emblazoned across the chest of her white turtleneck — just high enough not to lure the eye astray — she won the hearts of armies of American boys who had yet to win their first kiss.

To young female viewers, she was demure and unthreatening, a regular girl who might make a good friend. She described herself as a “late bloomer.”

Walt Disney, the impresario of the wholesome who was looking for young entertainers for “The Mickey Mouse Club,” was reported to have discovered Ms. Funicello in a school production of “Swan Lake.” She was the star.

The last of the children selected for the program, Ms. Funicello swiftly became the best loved. Her fan mail — 6,000 letters or more per week — demonstrated her popularity. An untold number of those missives proposed marriage.

“I really didn’t know how popular I was at first,” she once told film critic Gene Siskel. “I became a Mouseketeer when I was 12. Mr. Disney kept our fan mail from us because he didn’t want to start any jealousy. But then it got out of hand after about a year.”

When the show ended in 1959, she was the only “Mouse Club” member to be offered a Disney contract. She appeared in a number of Disney films, including “The Shaggy Dog” (1959), “Babes in Toyland” (1961) and “The Misadventures of Merlin Jones” (1964).

She reinforced her innocent image by recording such popular songs as “Tall Paul” and “Pineapple Princess.” A series of albums, including “Italiannette” and “Hawaiiannette (both 1960), sold millions of copies. She became a female counterpart to teen idols such as Frankie Avalon, Bobby Rydell and Paul Anka, whom she was reportedly dating at the time when he wrote “Puppy Love.”

In the 1960s, she appeared in a handful of beach movies with Avalon, including “Beach Party,” “Muscle Beach Party,” “Bikini Beach,” “Beach Blanket Bingo” and, finally, in 1965, “How to Stuff a Wild Bikini.”

Despite the films’ mildly naughty titles, Ms. Funicello’s clean-cut reputation remained intact.

“Go ahead and have fun — the good, clean fun,” Ms. Funicello recalled Disney saying. “But I have one request. I know everyone will be bikini-clad. I’d like you to look different. Would you wear a one-piece suit, or if it’s a two-piece, please don’t expose your navel.”

After the beach movies and several others — including “Head,” co-written by Jack Nicholson — Ms. Funicello, along with her fans, moved into the next stage of life and largely retreated from the public gaze to raise her children. She returned to American television sets chiefly as a promoter of Skippy peanut butter.

Over the years, she appeared in television shows such as “The Love Boat” and “Fantasy Island.” In 1987, she co-starred with Avalon in “Back to the Beach,” a film in which they poked fun at themselves. They played a settled-down, married couple whose teenage son at one point remarks, “A long time ago my parents were the most popular teenagers in the world.”

Throughout her life, Ms. Funicello retained popularity, at least in part, through her obvious modesty.

“When I say this, I don’t mean to slight any of my fellow Mouseketeers,” she wrote in her memoir, “A Dream Is a Wish Your Heart Makes.” But she said she believed much of the group’s appeal stemmed from creating the impressions that audience members could “sing as well as Annette, or . . . dance just like her.”

Annette Joanne Funicello was born Oct. 22, 1942, in Utica, N.Y. She grew up in Southern California, where her father, an auto mechanic, had gone to find work.

In her autobiography, co-written with Patricia Romanowski, Ms. Funicello said the watchfulness of the Disney company, and her family’s support, helped her avoid the problems that often ensnare child celebrities.

To avoid disillusioning her fans, Ms. Funicello hid later-life setbacks, at least for a time. Her first marriage, to her manager Jack Gilardi, ended in divorce. They had three children — Gina, Jack Jr. and Jason. In 1986, she married Glen Holt, a horse breeder.

Around that time, her illness was diagnosed. “I didn’t go public for a long time because I believed people wanted to think that nothing bad ever happens to Annette,” she told People magazine. “I didn’t want them to panic.”

In time, she spoke openly about the challenges of using a wheelchair and being limited in other ways. She told People that her “fantasy” was to go before Congress and ask anyone who had ever watched “The Mickey Mouse Club” to contribute a dollar to medical research.

She appeared to understand the degree of affection that surrounded her.

“Grown men,” Ms. Funicello once recalled, “always come up to me and say, ‘I was in love with you. You were my first girlfriend.’ ”