There's actually two or three somewhat different versions of the founding floating about.  All agree that Paul Opp was the prime mover.  

Yetta B. Mitchell, who worked with Paul Opp and was eventually national grand president, told it this way:
Paul Opp tried to get a charter for National Collegiate Players/Pi Epsilon Delta or from Theta Alpha Phi and was turned down because his school, Fairmont State, was one of the then new four year teacher's colleges and the older theatre honoraries weren't sure that counted as a "real"  college, since teacher's colleges had been two year "Normal School" programs until recently.

Opp then attended a summer  faculty conference of English, Speech and Theatre faculty people and proposed that the conference establish a new honorary - and the conference thought that was a great idea - except they didn't want to count theatre work toward membership. Opp and the other theatre people present (Yetta says they walked out of the meeting) later met in Paul Opp's hotel room and decided to set up an honorary of their own.  Paul Opp as National Business Manager , two of the others as President and Vice President.

Opp went back to Fairmont and recruiting two students to create the new group, Watson and Sloan who eventually became the first active members and, in turn, helped initiate the Alpha Chapter at Fairmont.

Other versions have a nice orderly process of a group of theatre faculty from different schools commissioning Paul Opp to set up a trial run chapter - or have Opp, Watson and Sloan setting up the Alpha Chapter and then recruiting other schools to join in.

But Yetta Mitchell's version of a bunch of throughly annoyed theatre people crowding into an un-airconditioned hotel room to set up what became the largest honorary on earth has a certain appeal to it.

I understand the chapter at Fairmont is back in business - perhaps they have some light to shed on their early history?