Jackie Townsend and her baby learned how to talk at the same time. Their teacher was her then 5-year-old son, Billy.

She learned how to tie her own shoes before the baby did, but not by much. Her son taught her that, too.

She still has a little trouble reading, and sometimes she'll grope for a word that simply does not come. But today, 11 years later, Townsend has become a powerful not-so-secret weapon for the American Heart Association, a dedicated foe of oral contraceptives--and a public speaker.

Jacquelyn Mayer Townsend had, by age 28, achieved the dreams of countless millions of American girls.

Lots of girls are pretty and talented and successful, but Jackie Townsend was more than pretty. She was Miss America.

She was more than just talented. Even before becoming Miss A, she toured with Fred Waring and the Pennsylvanians.

To top it off, she married the man she'd been in love with since she was a little girl. He was a successful lawyer, and they settled in on their Meadowlands, Pa., horse farm to raise their family . . . to live happily ever after.

And then, out of the blue--or, her doctors told her, more like out of a bottle of birth-control pills--the 1963 There-she-is-Mi-i-iss Amer-ri-ca was no longer beautiful (by the standards that had crowned her), nor talented. She could not walk at the start and could not speak--much less sing--for years. Her once dazzling smile now drooped to one side. One of her eyes drooped as well. But that was nothing compared to her spirit, at first.

"I remember," she says now, "lifting up my right hand with my left hand and it just dropped back, like it was dead. . ."

It was the morning after Thanksgiving 1970, when the fairy-tale bubble of Townsend's existence burst. She'd had a stroke doctors believed was induced by a single month on the Pill. (Her suit against the drug manufacturer was settled out of court.)

It was the first calamity of her young life. She had never wanted for anything, and virtually everything she ever wanted had been hers.

It was Fred Waring, she recalls, who started her on the road back. During the two weeks she was in the hospital he visited four times, rerouting his touring show to do so. He started encouraging her to talk, to relearn her ABCs. "I couldn't even get my mouth in the right position to say the letters."

Townsend's motor paralysis disappeared quickly: She walked out of the hospital. Still, she was unable to coordinate thoughts and words.

But as she fought her way back she began to believe that she had her stroke for a purpose. "I've always believed," she says, "that God opens many doors and closes many doors and guides you that way. Finally, I realized that the purpose was for me to go out and talk about it and help other people, give them hope that no matter what kind of adversity you face, you can overcome it."

When Jackie Townsend was "Miss A," she had been urged to go into public speaking. "I don't have," she said then, "anything to talk about."

After her stroke, when she was urged to speak about it, she had to say, "Now I have something to talk about, but I can't speak."

Townsend's husband, John, had urged her not to file suit against the company that made the birth-control pill she took because he feared she was not strong enough for court appearances. "If I don't do it, who will?" she asked herself. "I have to do it because of who I am."

It was this same determination that kept her working on her aphasia. The love, support and encouragement of her family and friends kept her going, she says, but perhaps most of all, it was because her kids laughed at her.

"You know," she says, and her yellow-flecked green eyes dance, "mothers all yell at their kids. But I found that I would yell at them to reprimand them for doing something they oughtn't, and the words wouldn't come out. Or they'd come out backwards. Billy would start laughing--first at me, and then with me.

"It was really good for me, because I began to see the humor. Even now when I get upset sometimes the words won't come, and now they're really laughing at me."

It took her four months to write her first 20-minute speech. Jackie Townsend's speeches today are about "trying." The "Miss A" smile, with only the merest (rather appealing) hint of crookedness, is now turned on to enlist volunteers and other backers for the American Heart Association. Last week she helped mobilize a conference of roller-skating-rink owners on behalf of A.H.A.

Townsend also talks personally to fellow stroke victims. "I know exactly what they're feeling," she says. "Frustration, anxieties, helplessness, depression. And so many times you have to remind the family they must have patience and there must be support and encouragement . . . constantly."

Townsend has starred in both a film and a brochure for the heart association: "A Different Kind of Beauty."

Recently she's begun to jog.

For information on AHA brochures on heart and stroke support groups, or the 10 1/2-minute film (or video cassette) of Jacquelyn Townsend's story, write the American Heart Association, National Capital Affiliate, P.O. Box 32409, Washington D.C. 20007 or phone 337-6400.