Gambaro was born in Oklahoma and grew up in Arizona. After moving to Washington, D.C., Gambaro and her husband Stephen owned and operated a very successful art gallery on Capitol Hill, which provided the venue to introduce many American Indian artists to the region. She was also the president of the Amerindian Circle at the Smithsonian Institution, which led the effort to create the National Museum of the American Indian. Gambaro chaired a star-studded gala at the Kennedy Center, which was the kick-off of the fundraising effort for NMAI.Gambaro, a Creek Indian, had worked in numerous other professions, including as a seamstress and a gallery owner, before turning to sculpture. She had promoted the work of other artists for years through her gallery, which specialized in American Indian art, and as part of the committee that helped push for the creation of, and raised funds for, the National Museum of the American Indian in Washington. Sculptures of Retha Walden Gambaro, both traditional and contemporary, fit somewhere in between.