The International Order of the Rainbow for Girls (IORG) is a Masonic youth service organization which teaches leadership training through community service. Girls, ages 11-21, learn about the value of charity and service through their work and involvement with their annual local and Grand (state or country) service projects.

The order was created in 1922 when a Mason, the Reverend W. Mark Sexson, was asked to make an address before South McAlester Chapter #149, Order of the Eastern Star, in McAlester, Oklahoma. As the Order of DeMolay had come under his close study and observation during his Masonic activities, he decided that another order for girls, setting forth some of the principles of Freemasonry, would be necessary.

The first Initiation consisted of a class of 171 girls on April 6, 1922 in the auditorium of the Scottish Rite Temple in McAlester. The original name was "Order of the Rainbow for Girls".