The Xenharmonic Alliance (XA), originally Xenharmonic Music Alliance, is a social group initiated by Ivor Darreg and Glen Prior around 1958 in Los Angeles, California.
In the beginning, the group held a series of meetings devoted to performing on new musical instruments and demonstrating xenharmonic scales. After Darreg and Prior had to move away from Los Angeles, the group kept going by correspondence, long-distance phoning and various publications. The group expanded as new members from across the United States, Canada, Mexico and abroad gradually joined the group. Several projects were born from these exchanges, such as the Sonic Arts center and the Interval journal.
More recently, the group expanded to the whole world through multiple online platforms. A Facebook group was created in 2007, with several more specialized ones created later on. An IRC chatroom was also created at some point, although it is mostly inactive nowadays as users moved to a Discord server created in 2017.