Na Casaidigh or The Cassidys are an Irish traditional group. They have been based in Dublin for many years, but they originally hail from Gweedore, County Donegal. The group consists of brothers Aongus, Seathrún, Ciarán, Fionntán, Feargus, and Odhrán. Irish is their native tongue and they had to study English as a second language during their school years. The brothers' music has attracted worldwide attention and brought them to audiences from Togo in West Africa to Carnegie Hall in New York City.
The Cassidys' father has long been a church choirmaster. He instilled his love of music, and Gaelic music in particular. Music instruction was woven through the boys' childhood. Piano or fiddle was introduced first, followed by other instruments that included whistles and pipes, bodhrán, and guitar.
All of the Cassidy brothers contribute to the group's harmonies. In addition, each plays several instruments. Odhrán studied the violin in Dublin, Vienna, and Manchester. He went on to play classical concertos with a number of orchestras. He is also accomplished on the uilleann pipes.