[3] While she was starting her teaching career in Mount Pleasant, South Carolina, she married the Reverend William Essex Forsythe, who ran the Holy Cross-Faith Memorial Church and School on Pawleys Island, South Carolina.

She continued to teach in Mount Pleasant and care for her parents, visiting Reverend Forsythe when she could.

In 1938, she joined her husband on Pawley's Island, and taught in a one-room school—the only local educational facility open to African-American children at that time.

[5] Affectionately known as "Miss Ruby", Forsythe taught for more than six decades,[4][5] even though she and her students were harassed by the Ku Klux Klan.

[6] She received four honorary doctorates, and was one of the subjects of the book I Dream A World: Portraits of Black Women Who Changed America, a collection of interviews and photographs by Brian Lanker.