Born Belle Marion Greener in Washington, D.C., to Richard T. Greener and Genevieve Ida Fleet, later becoming the celebrated librarian Belle da Costa Greene.
Belle Marion Greener was born on December 13, 1883, in Washington, D.C. She was the daughter of Richard T. Greener, the first Black graduate of Harvard College and a prominent lawyer, educator, and diplomat, and Genevieve Ida Fleet, a music teacher. Belle was one of several children born into a mixed-race family that was deeply embedded in African American intellectual and civil rights circles of the late nineteenth century.
Her birth came during the tumultuous era following Reconstruction, when racial classifications and the collapse of civil rights protections for Black Americans were hardening across the United States. This social climate would later shape one of the most consequential personal decisions of her life: as a young woman, she and her mother chose to present the family as white, adopting the surname 'Greene' and inventing a fictitious Portuguese heritage ('da Costa') to explain her complexion. This act of racial 'passing' allowed Belle to access opportunities—including her extraordinary career—that would have been closed to her as a Black woman in early twentieth-century America.
Her upbringing emphasized education and culture, setting the foundation for her later expertise in rare books, manuscripts, and art history. The circumstances of her birth and the racial reinvention that followed remain central to understanding her singular rise to power in the elite, overwhelmingly white world of American librarianship and art collecting.