MARY WELLS was just 17 when she became part of the Motown Sound, Detroit's big beat beehive, in the early '60s. Probably best known for her interpretation of "My Guy," written for her by Smokey Robinson, Wells was one of Motown's most consistent female hit-makers, with songs like "Two Lovers," "You Beat Me To the Punch" and "You Lost The Sweetest Boy."

"I wrote my first record when I was 15," Wells says on the phone from her Hollywood home. At 39, her voice is still soft and shy. "Rock 'n' roll and rhythm and blues were happening then; Presley, Little Richard and Bill Haley were happening, and it really hit me."

A Detroit native, like most of Motown's roster, Wells had been singing church songs since age 4 in the choir at her uncle's New Beulah Baptist Church. "All my uncles were either ministers or deacons and all the women were missionaries or Sunday school teachers," says Wells, who taught Sunday school herself until she hit the charts in 1961 with the self-penned shouter "Bye Bye Baby."

"A friend of mine in high school was dating a guy who worked with Motown Records founder Berry Gordy," Wells said. "I knew Berry was recording Jackie Wilson at the time, and I had this song. I thought, wow, it would be perfect for him. So they got me in to see Berry, and I didn't have any song sheets or anything. He just asked me to sing it for him.

"I didn't know about arrangements then, but I knew in my head what I wanted for the bass patterns, horns, strings. So I just sang all that for him," Wells recalls. After her acappella audition, Gordy signed Wells as the first artist on his fledgling Motown label, an offshoot of Tamla records. " 'Bye Bye Baby' stayed on the charts for about a year and a half," Wells says. "Motown didn't have national distribution then, so Berry would release a song in one city, then when it recouped the money, they did it in another city."

Gordy guided Wells through his star-maker machinery, grooming her for live engagements with the Motown Revue, and developing choreography and musical material for her. "Singing in church with all your relatives is one thing. Singing in front of a screaming audience is another thing," Wells says, remembering her nervousness about becoming one of Motown's top "girl singers."

"Berry tried out a number of writers with me, including the Holland Brothers (who went on to write many hits for the Supremes), and finally, Smokey Robinson was chosen for me." Wells was Robinson's first assignment as a producer and in addition to fronting his own group, the Miracles, he wrote, produced and arranged four Top Ten pop hits for Wells over a period of two years, including "My Guy" (1964), her only No. 1 hit.

"At that time, Motown had just gone nationwide, and the Beatles were over here, and they took our records over to Europe with them," Wells says. "The disk jockeys would ask them 'Who's your favorite singer?' And they would say, 'Mary Wells, Marvin Gaye . . . Motown groups.' I think Motown owes those guys a lot. They made us known in England; "My Guy" was No. 1 over there, and we suddenly thought, wow, we can make it all over the world."

Wells toured Europe with the Beatles, whom she describes as "perfect gentlemen," and recorded an album of Beatles tunes, called "Love Songs to the Beatles."

After three years with Motown, Wells, then all of 21, was lured to another label with a bigger contract but was unable to duplicate her success at Motown.

Wells, who now lives in Hollywood, says she's thankful her voice is still strong and continues to record. She had a Top Ten disco hit last year with the sassy song "Gigolo." "I thought I'd try something different," she says with a laugh.

These days, Wells says she performs "a little bit of everything" in her appearances, sometimes as a solo, more often on an oldies bill with other Motown and '60s stars. Wells will be at Constitution Hall next Saturday, sharing a bill with Ben E. King ("Spanish Harlem"), and the Shirelles, among others.

Despite the surfacing of horror stories about the Motown days, like Broadway's current "Dreamgirls," which portrays the hit factory as full of jealousy, backstabbing and underworld dealings, Wells says she still has fond memories of her time with Motown. "I always felt it was like a family. But I was always, and I still am, kind of naive. You call some of those people now, I won't name names, they're too busy or they don't return your calls. There's still that fear. I don't know why, they all should be pretty secure," Wells says. "But I just keep working and I don't even think about it."