She graduated from Seattle's Roosevelt High School and then attended the nearby University of Washington, where she received a degree in education in 1950. She married UW law graduate William H. Gates, Sr. in 1951, and she taught school in the early 1950s. After her husband co-founded the law practice that became Preston Gates & Ellis in Seattle, Gates turned to a variety of civic activities. Gates' volunteer roles in Seattle and King County included serving on the boards of the Children's Hospital Foundation, Seattle Symphony, Greater Seattle Chamber of Commerce, United Way of King County, and many other nonprofit organizations. She served as President of the Junior League of Seattle from 1966 to 1967.