Gershwin's opera took an unusual subject for the time: the lives of poor Southern blacks as told by DuBose and Dorothy Heyward in their 1927 play Porgy. As the title might suggest, Bess was a minor character in the Heyward drama, but Gershwin expanded the role. It did not hurt matters that the young and pretty Ms. Brown was often by his side, showing him how the music would sound when she sang it. It was she would suggested to Gershwin that Bess sing "Summertime" in the third act, reprising the song the character Clara sings earlier.

Ms. Brown would play herself in "Rhapsody in Blue," the highly fictionalized film about the life of Gershwin, who died in 1937.

Following Porgy and Bess, Ms. Brown appeared in the revue Pins and Needles; two separate runs of the Heyward play Mamba's Daughters; and a 1942 revival of Porgy and Bess at the Majestic Theatre. This latter production did better than the original, running 286 performances — a measure of the opera's growing reputation.

After 1948, however, Ms. Brown's life was in Oslo, Norway, where she decided to live after years of concertizing all over the world. She became a Norwegian citizen. The singer said the racism in America drove her away. "Many things that I wanted as a young person for my career were denied to me because of my color," she said. In Europe, she sang the works of Brahms, Schubert, Schumann and Mahler.

When asthma forced her to end her career as a singer in the 1950s, she became a teacher, taking on students such as the famous soprano Elizabeth Norberg-Schulz and actress Liv Ullmann. She also staged several operas in France and Norway. Ms. Brown was born Aug. 9, 1912, in Baltimore, MD, the daughter of Harry F. Brown, a middle-class physician, and his wife, the former Mary Allen Wiggins. She trained at Morgan College and then was accepted as the first black vocalist admitted to the New Institute of Musical Art (now known as the Juilliard School). She would win the Margaret McGill prize as the best singer at Juilliard. Still, prejudice kept her out of many of the leading opera houses, including the Met.

It was while she was at Juilliard that she read that Gershwin was writing his opera, according to the New York Times. She wrote requesting an interview. Given the go-ahead, she arrived with a armload of classical music. Wrote the Times, "When he asked her to sing a Negro spiritual, she balked. She considered the request racial stereotyping, but finally sang 'A City Called Heaven' without accompaniment. Gershwin was quiet after she finished. He finally told her that it was the most beautiful spiritual he ever heard. They hugged."

Ms. Brown was married three times, first to Florid Howard, a fellow Juilliard student, when she was 19; then to Dr. Jacob Petit, with whom she had a daughter, Paula. Ms. Brown's marriage to Thorleif Schjelderup, who was an Olympic ski jumper at the 1948 Winter Olympics, ended in divorce. She is survived by her daughters Paula (who changed her name) and Vaar Schjelderup; four grandchildren; and three great-grandchildren.