PiBetaPhi,

I believe the original question asked which was first--not when it was nationally organized.

ADPi (founded as the Adelphean Society) was the first secret society for women and it was indeed founded first, followed by Phi Mu (the Philomathean Society). Pi Beta Phi (founded as I.C. Sorosis) was founded in 1867 (as stated earlier).

As ecukd said, it all depends on what you consider a sorority. Kappa Alpha Theta was the first women's organization founded with Greek letters...whereas Gamma Phi Beta was the first organization to use the word "sorority".

After considering all of this, I'd think that ADPi was the first secret organization for women, Theta's the first women's GLO, and GPhiB's the first "sorority".

That probably didn't answer your question--but I know that this topic has been discussed before and perhaps those threads can be of help to you.