Delta Sigma Theta (ΔΣΘ) is a not-for profit Greek-lettered sorority of college-educated women dedicated to public service with an emphasis on programs that target the African American community. Delta Sigma Theta Sorority was founded on January 13, 1913, by 22 collegiate women at Howard University. These students wanted to use their collective strength to promote academic excellence and to provide assistance to persons in need. The first public act of Delta Sigma Theta was the Women's Suffrage March in Washington D.C., on March 3, 1913. Today, Delta Sigma Theta Sorority is the largest African-American Greek-lettered organization. Membership in Delta Sigma Theta is open to any woman who meets the membership requirements, regardless of religion, race, or nationality. Women may join through undergraduate chapters at a college or university, or through an alumnae chapter after earning a college degree.

Since its founding, Delta Sigma Theta has been at the forefront of creating programming to improve political, education, and social and economic conditions. Delta Sigma Theta has been pivotal in assisting the African American and International communities through education, lobbying, and economic initiatives, including Delta Days at the State and Nation's Capitol, Delta Days at the United Nations, Summits and various conferences which focus on pertinent issues of the day. In addition to establishing independent programming, The Sorority consistently collaborates with community and corporate organizations such as Chase, Habitat for Humanity, Coca-Cola, Wal-Mart, Lawry's, and General Electric to further its programming goals.

A sisterhood of more than 300,000 initiated members who are predominantly black college-educated Women, the sorority currently has over 940 chapters located in the Bahamas, Bermuda, Canada, England, Germany, Jamaica, Japan (Tokyo and Okinawa), Liberia, South Korea, United States of America and Virgin Islands. Delta Sigma Theta is a member of multiple organizations, including the National Pan-Hellenic Council (NPHC) – an organization of nine international Greek-letter sororities and fraternities – as well as the NAACP and the National Council of Negro Women (NCNW). The current 26th national president is Beverly Evans Smith.

The organization kicked off its centennial year celebration by being the first Black Greek Lettered Organization to participate in the Tournament of Roses Parade in Pasadena, CA on January 1, 2013 with a float entitled "Transforming Communities through Sisterhood and Service."