Rachel Epstein has been involved in activist work since at least the 1960s. While living in Vancouver, she worked with and for the International Committee Against Racism, helped found the Labour Advocacy and Research Association (LARA), did typesetting and publishing work for New Star Books and Press Gang (both activist publishers), worked with and for the Women’s Research Centre (WRC), and helped organize events for International Women’s Day (1977 and 1979). She was also involved with various feminist groups, including Act Up, a participatory theatre group.

Epstein later moved to Toronto where she worked for the Participatory Research Group (PRG), with which group she served as the North American coordinator for an international conference on the impact of micro-technology (microchips) on women’s work. After leaving the PRG, she worked as a coordinator for Second Look Community Arts, specifically with their Theatre of the Oppressed program, then as a teacher at Seneca Community College in the women in trades and Ontario basic skills programs. She received her Masters of Arts in Sociology from York while working at Seneca. She helped develop the Dykes Planning Tykes program for The Queer Exchange; with her female partner, Epstein had a daughter, Sadie, in 1992 using a sperm bank at a fertility clinic, an experience which she used along with interviews and research to help build up a community for LGBTQ+ prospective parents in Toronto. She started working for the LGBTQ (then LGBT) Parenting Network circa 2001 and was still working for them at the Sherbourne Health Center in 2015. She also partnered with a researcher at the Centre for Addiction and Mental Health (CAMH) on several projects surrounding LGBTQ+ parenting and fertility clinics, and through that research became involved with the Assisted Human Reproduction Agency; she has served on several committees for that group.

Throughout her career, Epstein has published papers, articles, and contributed to various books and anthologies. Her book Who’s Your Daddy, a collection of writings on LGBTQ+ parenting and family planning, was published in 2009. She was the recipient of the Steinert Ferreiro Award (Community One Foundation) in 2008.