| Letters: | Greek, Ancient (to 1453);: ΤΓΣ |
| Tau Gamma Sigma | |
| Crest: | Tau Gamma Sigma Emblem.jpg |
| Birthplace: | University of the Philippines |
| Affiliation: | Independent |
| Status: | Active |
| Type: | Service Sorority |
| Scope: | Local |
| Motto: | "A Triskelion firmly believes in the power of reason and not in the use of force as reason." |
| Colors: | Gold Green Black |
| Symbol: | Lady Triskelion (general) |
| Patron Saint: | St. Anthony the Great |
| Chapters: | 1 |
| Address: | University of the Philippines Diliman |
| City: | Quezon City |
| State: | Metro Manila |
| Country: | Philippines |
| Pillars: | Fortis Voluntas Sororitas (Strength, Freewill and Sisterhood) |
| Mascot: | Lioness |
Tau Gamma Sigma (Greek, Ancient (to 1453);: ΤΓΣ) also known as the Triskelions' Grand Sorority, is a sorority established in the Philippines. Its members call themselves Lady Triskelions.[1] Its fraternity counterpart is Tau Gamma Phi (Greek, Ancient (to 1453);: ΤΓΦ) also known as the Triskelions' Grand Fraternity.
On January 17, 1969, Tau Gamma Sigma was founded by ten women from the University of the Philippines Diliman. The founders were friends of the Tau Gamma Phi fraternity founders. The women were all political science students and members of the same political science club as the founders of Tau Gamma Phi. The first initiation rites were held in Bustos, Bulacan. Successive batches followed until they reached fifty members from different colleges in UP Diliman. The formal sorority structure was ratified in July 1970.
After the declaration of martial law in 1972, the shared office of Tau Gamma Phi and Tau Gamma Sigma inside UP Diliman was raided under an arrest-search and seizure order signed by then-secretary of defense Juan Ponce Enrile, which resulted in the confiscation of several subversive materials and documents. Both the sorority and the fraternity were critical of the Marcos administration.
The sorority's colors are gold, green, and black. Its patron saint is St. Anthony the Great. Its pillars are Fortis Voluntas Sororitas or Strength, Freewill, and Sisterhood. Its symbol is Lady Triskelion and its mascot is the lioness. Its anthem is the ''Triskelion Hymn''.