In 1900, Foster joined the Morristown Lawn Tennis Club.E2 Project Management LLC. Historic Structures Report: The Willows at Fosterfields: An update to the 1983 Historic Structures Report by Robert P. Guter, 2015. Accessible via the archives of the Morris County Park Commission. In 1903, Foster joined the Morris County Golf Club. She was also involved in the Morristown Library's Modern Mondays, a monthly reading club that included anthropologist Ethel Cutler Freeman, author Dorothy Kunhardt, and Elinor Parker, manager of Scribner's Book Store.
