Rebecca Fox is a senior program officer for the Sexual Orientation and Gender Identity (SOGI) program at the Wellspring Philanthropic Fund, a left-of-center foundation founded by three hedge fund billionaires. Fox is a career activist for left-of-center causes, particularly abortion access, health care, and LGBT-interest issues.
Fox took a position for the National Partnership for Women and Families, a nonprofit which advocates left-of-center positions on legislation concerning women.  Then, Fox worked as the assistant director for public policy at the Sexuality Information and Education Council of the United States (SIECUS), a nonprofit that promotes sexual education in K-12 schools. In her role, she worked at the state level to oppose abstinence-only education in individual school districts. 
Fox became the executive director of the National Coalition for LGBT Health, a nonprofit which advocates for increased health service access for LGBT individuals. 
In Fox’s current position as the senior program officer of the Sexual Orientation and Gender Identity program at Wellspring, she manages grantmaking to nonprofit LGTBQ+ advocates. 
Throughout the mid-to-late 2000s, Fox sat on the boards of numerous public health nonprofits based in Washington, D.C. She was on the community advisory board for the lesbian services program at Whitman-Walker Health, an LGBT-focused community health center.  She also sat on the board of the Washington Area Clinic Defense Task Force, a nonprofit which provides escorts and protection for women seeking abortions at government-funded clinics. Fox served on the board of the Woodhull Freedom Foundation, a nonprofit that advocates for LGBT and social-liberal women’s interests.  Fox also sat on the board of Choice USA, a now defunct national organization that mobilized pro-abortion advocates. 
In the 2010s, Fox took positions on more nonprofit boards. She was on the board of Generations Ahead, a Michigan-based organization which supports young single mothers, and Jews for Racial and Economic Justice, a New York-based left-of-center social and economic policy advocacy organization. Fox continues to sit on the board of Funders for LGBTQ Issues and the steering committee of the International Trans Fund.