After receiving her doctorate in Counseling and Personnel Services from the University of Maryland, Dr. Sandler sought out a faculty position at the school for which she was particularly well qualified for. She was denied the position because she came on "too strong for a woman." Ever since encountering that act of discrimination, Dr. Sandler has fought for the rights of women in the field of education.

While volunteering for the Women's Equity Action League from 1969 to 1971, Dr. Sandler worked to enforce an Executive Order signed by President Lyndon Johnson that prohibited sex discrimination within organizations with federal contracts. While most universities did not have policies eliminating gender discrimination, most had federals contracts. Dr. Sandler filed sex discrimination complaints against 250 institutions under this Executive Order. With Representative Edith Green, she went on to spearhead hearings that documented discrimination in employment and educational opportunities. These hearings lead to the passage of Title IX and other laws eliminating overt discrimination in education. Dr. Sandler's key role in the creation and implementation of this law gave her the nickname, the "Godmother of Title IX."

Dr. Sandler has been a part of many "firsts" in the fight for gender equality. In 1970, she was the first person to testify before the U.S. Congress about gender discrimination in education. She then became the first person appointed to the staff a Congressional committee specifically for issues concerning women's rights. In 1971, Dr. Sandler, working with the U.S. Department of Health, Education, and Welfare, wrote the first federal policy report regarding sex discrimination in education. As a result of these efforts, Dr. Sandler was appointed to chair the first federal Advisory Committee on Women's Educational Equity.

Dr. Sandler's "firsts" extend to many reports she wrote on gender equity. She wrote the first report on peer harassment in the classroom and the first report examining the process and procedures used to nominate and award campus prizes that inadvertently exclude women. Dr. Sandler also wrote the first report on campus gang rape and the first report providing search committees with questions to determine how supportive potential faculty or administrative members were of gender equality. In 1982, she wrote the first report on the chilly campus climate, a term Dr. Sandler coined to describe how small unknown behaviors can have a detrimental impact on women's ambition, contribution, and self-esteem. In 1989 and 1990, Dr. Sandler wrote the first reports on the chilly climate faced specifically by African American and Hispanic women on campus.

In the courtroom, Dr. Sandler has served as an expert witness in many cases involving sexual harassment or discrimination in educational institutions or the workplace. Her publication, "10 Ways Expert Witnesses Can be Used in Sex Discrimination and Sexual Harassment Cases," has served as a standard reference for educators, lawyers, and bar associations since its publication in 1997.

Dr. Sandler's work for gender equity in education is extremely extensive. She has written over 100 articles, served on over thirty boards, given over 2,500 presentations, and appeared in many major media outlets, including the New York Times, Sports Illustrated, and Larry King Live. Her books comprise of, The Chilly Classroom Climate: A Guide to Improve the Education of Women, Sexual Harassment on Campus: A Guide for Administrators, Faculty and Students, and Peer Sexual Harassment, K-12. She has received numerous honors for her work including the "Century of Women Special Achievement Award" from the Turner Broadcasting System and over ten honorary doctorates.