The Portia Sorority was organized in 1933 and was originally known as the Portia Club. The former Dean Jorge Bocobo noted a significant increase in the number of female law students enrolled in the UP College of Law. He thought it necessary that the women students group themselves into an organization to attain harmony in their relations with one another, and to achieve maximum affectivity in campus activities.

Pacita Delos Reyes - Phillips, a noted lawyer, beauty queen, and social figure, was the Portia Club's first Lady President. The founding members were some of the well-known women in the legal profession, including Justice Cecilia Munoz-Palma, Corazon Juliano- Agrava, Felisa Dela Fuente-Samson, Elvira Bocobo-De Castro, Sumilang Bernardo, Eugenia Banzon-Jose, Liwayway Bacarin-Fuentes, Angelica Bellarmino, Salud Oliveros-Lustre, Elisa Santillan, Remedios Acosta Azurin, Elisa Estrella-Hilario, Felicidad Arce, Clarita Cartera, Lydia Lorento, Angelica Mara-Santos, Flor Liza Valino-Rajonera, Beatriz Talavera-Morales and Olivia Calupang-Causing.

Portia started out as a mere social organization, counting among its activities tea parties at the Lady President's residence, organizing exclusive social affairs and participation in the annual Law Jamboree Day. The club also actively participated in university gatherings and social activities sponsored by other colleges.

In 1935, during the presidency of Felisa dela Fuente, the club decided that in addition to providing a social outlet for its members, it should also adopt a program of activities conducive to the cultural development of its members. The Portia Club then started to sponsor convocation programs, symposia, and debates. They were also very active in campus politics. In fact, Portia's President and Vice-President were accorded automatic membership in the Student Council. This privilege was enjoyed by the Club until 1953.

The outbreak of World War II brought with it the suspension of all the UP Organizations' activities, including the Portia Club's. The war also brought with it the destruction of the Club's records.

In 1945, Lady President Gregoria Arnaldo–Cruz appointed Amuerfina Melencio-Herrera and Emma Quisumbing-Fernando to draft a new constitution for the Club. The year 1946 was a momentous year for the Club. Under Lady President Amuerfina Melencio-Herrera, bar top-notcher and former Justice of the Supreme Court, the new constitution became operative and the Club became a Sorority. The Portia Sorority acquired an exclusive home on campus, the Portia Room, during AY 1950-1951. Under the presidency of Concepcion Lim-Jardaleza, in 1974, Portia became instrumental in initiating Philippine Participation in the Annual Jessup Moot Court competition in International Law. In 1995, the UP Law Jessup Team headed by Portians Lui Bunggo and LP Suzette Suarez, bagged top honors in the competition held in New York. Portia's members are also constant participants of the annual Pi Sigma Debate Tournament in UP, winning the championship in 1993, and finishing as first runner-up in 1998, and 2003.

Through the years several Portians have also served their fellow students through positions in the University Student Council, Law Student Government and the College of Law Electoral Judicial Tribunal. The most recent of whom have been Azela Guerrero Arumpac (USC Vice-Chairman), Jessica Ramirez Vitug (LSG Treasurer), Anna Christina Rosales Iglesias (USC Councilor), Grace Panganiban Garcia (LSG Secretary), Bai Ashrafia Aymee Alonto Biruar (EJT Vice-Chairman) and Sandra Jill Soriano Santos (USC Councilor).

Today, Portia continues to be dedicated to a culture of excellence, and social relevance. This has placed many sisters in the illustrious membership of the Order of the Purple Feather, the UP Law's Honor Society. Portia through its activities, honorably planned and lovingly executed, continues to live up to its tradition of excellence.