Winona Cargile Alexander was a founder of Delta Sigma Theta sorority, Incorporated at Howard University on January 13, 1913. It was the second sorority founded by African-American women and was influential in women's building civic institutions and charities. In 1915, she was the first African-American admitted to the New York School of Philanthropy, where she received a graduate fellowship for her studies. She was the first African-American hired as a social worker in New York.

Delta Sigma Theta Sorority, Inc. (ΔΣΘ) is a historically African American sorority. The organization was founded by college-educated women dedicated to public service with an emphasis on programs that assist the African American community. Delta Sigma Theta was founded on January 13, 1913 by twenty-two women at Howard University in Washington, D.C. Membership is open to any woman, regardless of religion, race, or nationality. Women may apply to join through undergraduate chapters at a college or university or through an alumnae chapter after earning a college degree.