Alpha Phi Omega (ΑΦΩ), commonly known as APO, but also A-Phi-O and A-Phi-Q, is a coeducational service fraternity. It is the largest collegiate fraternity in the United States, with chapters at over 350 campuses, an active membership of over 25,000 students, and over 400,000 alumni members. There are also 250 chapters in the Philippines, one in Australia and one in Canada. The 500,000th member was initiated in the Rho Pi chapter of Alpha Phi Omega at the University of California, San Diego.