Theta Xi (ΘΞ) is a social fraternity founded at Rensselaer Polytechnic Institute on April 29, 1864; it is uniquely the only fraternity founded during the Civil War. The fraternity has around 50 active chapters and colonies across the United States, with over 60,000 initiated members. Theta Xi is divided into two entities: the Theta Xi Fraternity and Theta Xi Foundation. The motto of the fraternity is Juncti Juvant: "United they Serve".