The Kossoy Sisters are identical twin sisters who performed American folk and old-time music. Irene sang mezzo-soprano vocal, and Ellen supplied soprano harmony, with Irene on guitar and Ellen playing the five-string banjo in a traditional up-picking technique. Their performances were notable examples of close harmony singing. They began performing professionally in their mid-teens and are esteemed as a significant part of the popular folk music movement that started in the mid-1950s.