Marjorie Phillips would have protested the title of "Grande Dame," though she had earned it as one of Washington's last. Mrs. Phillips, who died yesterday at the age of 90 of pulmonary failure, lived in a grand mansion with a great art collection, had a circle of social and intellectual friends and was known as a charming hostess.

But she preferred another title: artist. And by her talent and her work spanning more than 70 years, she earned it. In 1977, when she was 81 years old, she had a one-woman show at the Franz Bader Gallery. Last October she celebrated her birthday with a retrospective at the Phillips Collection. If the paint was dry on all of the paintings, it wasn't dried hard, for she painted right up until 1982, when her energies were still strong but her eyesight was not.

Finally, Marjorie Phillips earned yet another title: patron of the arts. In 1921, with her husband Duncan, she founded the Phillips Collection, the first museum of modern art in the United States. She was an adventurous and innovative patron, encouraging and buying the work of Bonnard, Renoir and Monet.

She grew up in a day when her father thought the life of an artist too bohemian for her gentle upbringing. But she married a man who believed in her as an artist while adoring her as a woman. For years, until his death in 1966, they worked in adjacent rooms, his study, her studio. She wrote a book, "Duncan Phillips and His Collection," which is a charming love story.

Money, talent and love are not always enough, but she triumphed over her great tragedies: the lifelong illness of her daughter, the illness of her beloved brother and, most difficult of all, the death of her husband. Mrs. Phillips also triumphed over the indignities of old age with her great style and her good humor. The night before she died she spent the evening drinking champagne with her son Laughlin. They talked about the pleasures and pride she had in her son, who succeeded her as director of the Phillips, and of her granddaughter Liza, an artist, and her grandson, Duncan, an apprentice architect.

Earlier in the day she was in the midst of checking the final proofs of her book, "Marjorie Phillips and Her Paintings," to come out in three months. "She was very particular, she'd send a painting proof back three and four times," said her son.

Mrs. Phillips was an amusing and revealing writer. She perhaps explained her own life best in two quotations from her forthcoming memoirs:

"I decided to paint the celebration of the wonder of the world. I didn't want to paint depressing pictures. There were so many depressing things; so many self-conscious, forced, foolish things. That's why my paintings are all on the cheerful side -- I felt it was needed. There are the two sides, but it's hard to get in everything."

On another page she wrote what could well be her own epitaph:

"My days were spent juggling different roles: painting in the mornings; running the house; being a mother; fulfilling social responsibilities, which we kept at a minimum; and, after Duncan's death, in 1966, running the Gallery until Laughlin took over in 1972. I didn't mind it because I had so many satisfactions. I was happy as long as I had some time to paint every day."