Singer Diana Ross has become a part-owner of Motown Records, and has agreed to resume recording for the label she helped propel to popularity in the 1960s.

The size of her investment in the company wasn't revealed when the deal was announced this week.Motown founder Berry Gordy Jr. sold the company in June to a partnership of MCA Inc. and Boston Ventures, an investment firm, for a reported $61 million. At the time, a Motown spokeswoman said Ross had intended to return to Motown.

MCA didn't say how her investment might fit in with the company's promise to maintain 20 percent minority ownership in Motown, once considered one of the nation's largest and most successful black-owned businesses.

Ross, who recorded on Motown with the Supremes in the 1960s but who left the label in 1980 to sign with RCA records, signed an exclusive contract with the new Motown, the company said. Her first new Motown album, "Workin' Overtime," is scheduled for release in early May.

- MEANWHILE, ROSS SAYS she is determined to do something different as she returns to the stage after taking time out to marry and give birth to two sons.

"People expect glitter and glitz from me," Ross said in an interview in the March issue of Vanity Fair magazine. "But you have to change, too. . . . You have to keep cutting the strings all the time."

For the moment, Ross, 44, is planning to finish her new album and go on a concert tour.

Her career was launched in the 1960s as the Supremes' lead vocalist, and she says she has a "motherly instinct" toward the young black singers of the 1980s.

"I love Whitney (Houston)," Ross said.

But envy of Houston's success is what propelled her to resume her career, according to a friend who is quoted anonymously by the magazine as saying, "Diana would be competitive with a tree."

"I have to be better than the best. Super-everything," said Ross, who has been keeping a low profile lately.