Alpha Omicron Sigma (AŌΣ) is a Puerto Rican fraternity established in 1957.
|Alpha Omicron Sigma|
Pontifical Catholic University of Puerto Rico
|Motto||Igualdad, Justicia y Fraternidad|
|Colors||Yellow, white and purple|
The Honorable Alpha Omicron Sigma Fraternity was established during the months of August and September of the year 1956, and was initially called Alpha Phriggia Sigma, through the efforts of a group of young students from the Pontifical Catholic University of Puerto Rico in Ponce, the which were aware of a fraternity where the principles of Equality, Justice and Fraternity were practiced to capacity. It was on April 1, 1957, when it was officially incorporated as a non-profit corporation by being registered in the Registry of Corporations and Entities of Puerto Rico.
The fraternity has actively participated in different charitable activities such as "Rapados por una Causa II', which translates to "Shaved for a cause II", for the Cabezitas Rapadas foundation which assists economically and emotionally cancer patients in radio and chemotherapy. 
The fraternity has also participated in the collection of shoes of both genders for people with needs to later be delivered to the charity organization "Soles4Souls" Capítulo de Puerto Rico.
After the 2010 Haiti earthquake, the fraternity was also collecting essential items to be donated to those affected by the earthquake.
- Alpha – Ponce
- Beta – Río Piedras 
- Gamma – Mayagüez
- Delta – Arecibo
- Epsilon – San Germán
- Zeta – Aguadilla
- Eta – Humacao
- Kappa – Cayey
- Omega – Utuado
- ^ "FRATERNIDAD ALPHA OMICRON SIGMA, INC". Registry of Corporations and Entities. Retrieved 18 January 2022.
- ^ Sullivan, Pat (8 May 2016). ""Rapados por una Causa II"". El Vocero de Puerto Rico (in Spanish). Retrieved 18 January 2022.
- ^ "Recogen zapatos por una causa". Issuu (in Spanish). Periódico El Regional. 29 October 2014. p. 18. Retrieved 18 January 2022.
- ^ "PUCPR" (in Spanish). Archived from the original on 2008-01-12. Retrieved 2008-01-03.
- ^ Alba Carballo, Mario (29 January 2016). "Parrandón para el reclutamiento de jóvenes escolares a la IUPI". UPR Río Piedras. Retrieved 18 January 2022.
- ^ "ORGANIZACIONES ESTUDIANTILES" (PDF). UPR Cayey. Retrieved 18 January 2022.
- ^ "CASA CLUB FRATERNIDAD ALPHA OMICRON SIGMA ZONA PASIVA NORTE INC". Registry of Corporations and Entities. Retrieved 18 January 2022.
- ^ "ZONA PASIVA SUR ALPHA OMICRON SIGMA INC". Registry of Corporations and Entities. Retrieved 18 January 2022.
- ^ "ZONA PASIVA Utuado ALPHA OMICRON SIGMA INC". Registry of Corporations and Entities. Retrieved 18 January 2022.