Margaret Olivia Slocum Sage, known as Olivia Sage, was an American philanthropist known for her contributions to education and progressive causes. In 1869 she became the second wife of industrialist Russell Sage. At his death in 1906, she inherited a fortune estimated at more than $63,000,000, to be used at her discretion.

Russell Risley Sage was an American financier, railroad executive and Whig politician from New York, who became one of the richest Americans of all time. As a frequent partner of Jay Gould in various transactions, he amassed a fortune. Olivia Slocum Sage, his second wife, inherited his fortune, which was unrestricted for her use. In his name she used the money for philanthropic purposes, endowing a number of buildings and institutions to benefit women's education: she established the Russell Sage Foundation in 1907 and founded the Russell Sage College for women in 1916.