Eduardo Z. Corpuz and a group of service-oriented young men from the College of Agriculture organized the ALPHA PHI OMEGA (APO) Service Fraternity at the University of the Philippines - Los Baños (UPLB) in 1956. The National Council officially recognized APO in UPLB as the 8th collegiate chapter of APO Philippines on 14 February 1958 and was thus designated as THETA CHAPTER.
With the founding of Theta Chapter in 1956, the sorority on record associated with APO in UPLB was the Kappa Phi Omega (KPO), which was founded on 1 August 1957. Before it was officially recognized by the National Council of APO, the KPO changed its name to Alpha Phi Sigma, which it used between 1965 and 1966. On 14 January 1970, it was agreed that all sororities seeking recognition from the National Council of APO Philippines collectively use the name Alpha Phi Omega Auxiliary Sorority (APOAS). This changed during the 10th Biennial Convention when the sorority was renamed as the ALPHA PHI OMEGA Service Sorority (APOSS) in full recognition of the sorority's equal and distinct status.
Owing to the dynamism of its founders, active collegiate (resident) members, and alumni, Theta Chapter became renowned not only in its home campus but also among other chapters of APO Philippines. In fact, many Thetans went on to become founders or co-founders of other chapters across the country. Through the years, Theta Chapter had been involved in a variety of service projects on campus, and played different roles either as initiators, co-organizers or participants.
Being faithful to its legacy and committed to upholding the cardinal principles of Leadership, Friendship and Service, chapters of Alpha Phi Omega bonded to render service to all sectors of society, and made full use of their creativity and resourcefulness. From the most humble to the most ambitious projects, Theta Chapter responded and continues to respond to the challenges of the times. Through their achievements and despite later challenges and even some shortcomings, Thetans of every generation have made their mark in various fields as THE Talented Achievers.
APO Theta UPLB prides itself in its capacity to bring out the best in young men and women. Theta Chapter has not only produced leaders who are responsive to the needs of society, but has also stamped a unity among its active collegiate (resident) and alumni members that allow them to carry with conviction the principles and ideals of Alpha Phi Omega. They share the same storied past and serve together in the present to forge a common future of a stronger and more united APO Theta UPLB, ever striving to play its distinct and exemplary role as the foundry of LEADERS IN FRIENDLY SERVICE.
Today, the men and women of Theta Chapter recognize the need to sustain its treasured traditions while redirecting the organization to be more attuned to the present challenges. APO Theta UPLB continues its effort to be as true as it could be to the ideals first espoused by Frank Reed Horton and to the common goals of all chapters of Alpha Phi Omega. In the heart of every Thetan beats the truth that the ultimate expression of freedom is to live a life dedicated to the service of others.