Sweet Adelines International is a worldwide organization of women singers, established in 1945, committed to advancing the musical art form of barbershop harmony through education and performances. This independent, nonprofit music education association is one of the world's largest singing organizations for women. "Harmonize the World" is the organization's motto.  It has a current membership of 21,000 and holds an annual international singing competition.

Sweet Adelines International was established in 1945 by Edna Mae Anderson of Tulsa, Oklahoma. The aim was to teach and train its members in music and to create and promote barbershop quartets and other musical groups.[3] She gathered a group of women who wanted to participate in the "chord-ringing, fun-filled harmony" that their husbands, members of the men’s Society for the Preservation and Encouragement of Barbershop Quartet Singing in America (SPEBSQSA), were singing. SPEBSQSA has since changed its name to the Barbershop Harmony Society. 

By year's end, the first chapter incorporated in Oklahoma with Anderson as its president. It had 85 members and a chapter name, Atomaton (for "an atom of an idea and a ton of energy") that recognized the Atomic Age. 

Sweet Adelines went international on March 23, 1953 when the first chapter outside the U.S. was chartered in Brandon, Manitoba, Canada. Even though there were international chapters, it wasn’t until May 1991 that the name officially changed to Sweet Adelines International. 

Sweet Adelines International has a very diverse membership that spans the globe. The organization includes women from a wide range of backgrounds who love to sing.