I cannot be sorry at Mercedes de Acosta's death. I am only sorry that she should have been so unfulfilled as a character. In her youth she showed zest and originality. She was one of the most rebellious & brazen of Lesbians. . . . I am relieved that her long drawn out unhappiness has at last come to an end. - Upon her death Cecil Beaton wrote this as an epitaph in his diary.

Descended from a noble and proud Spanish family, Mercedes de Acosta's orphaned mother,  Micaela Hernandez de Alba y de Alba, had traveled to the United States at the age of fourteen, where she had fought her case successfully with the New York Supreme Court for the return of the family fortune that had been absconded by her sinister uncle.

Mercedes's father, Ricardo de Acosta,  had migrated from Spain to Cuba, where he supposedly had led a group of revolutionaries attempting to overthrow Spanish rule. The story goes that he was arrested, escaped from a firing line, and fled to New York where he eventually met Mercedes's mother. He convinced his future wife to remain in the United States and marry him rather than return to Spain with her inheritance.

Mercedes des Acosta, along with her parents and seven siblings, lived in New York City on fashionable Forty-seventh Street, between Fifth and Sixth Avenues, where their neighbors included such personalities as former President Theodore Roosevelt, and the William Vanderbilts. Mercedes's parents often took part in the genteel, social activities of the neighborhood.

The escapades of her beautiful older sister, Rita also known as Rita Lydig,  were often mentioned in the society sections of the daily newspapers. She  posed for paintings by several artists--Rodin and Boldini. Malvina Hoffman sculpted an alabaster bust of her. Her personal wardrobe became the basis for the start of the Costume Institute at the Metropolitan Museum of Art.

When Mercedes published her autobiography, Here Lies the Heart ,  in 1960, it received excellent reviews, but sales were slim.  Even though the book discusses all her female friends with no direct reference to their lesbianism, many readers were outraged by the implications. Some of the women mentioned in the book felt they had been "outed." Garbo snubbed her on the sidewalks of New York and refused to see Mercedes even when she was on her death bed.  Le Gallienne never forgave Mercedes. When a friend found a gold wedding band in Eva's attic some ten years after Mercedes had died and asked what it was, Eva snatched it away, threw it down a well outside her home, and grumbled, "It was from Mercedes." If Le Gallienne was in a room and heard Mercedes name mentioned, she would storm out of a room in disgust. Le Gallienne told everyone that she thought the book should have been called "Here the Heart Lies and Lies and Lies."

When she died in 1968 she was penniless and living in a tiny, two-room apartment in New York City.  She is buried at Trinity Cemetary in New York City.