Carolan is known today for instrumental music, but most of the tunes attributed to him do or did have words which he composed. A number of his tunes are actually older tunes, which he re-set for his songs.
Carolan's music is notable for combining different influences. As an Irish harper in the 18th century he had been trained in the old Gaelic oral tradition of harp playing and composing. He also is said to have had a fascination with the latest Italian music that was the height of fashion in Dublin. And there is an element of folk-song in his music as the old Gaelic order, which maintained harpers and poets as high-status artists, was collapsing, and like the other 18th century harpers he had to find work where he could.
Carolan composed instrumental music as well as songs for his patrons. He is said to have composed "Carolan's Concerto" when staying with an Italian composer at the house of an Irish nobleman. But its other title, "Mrs Poer" suggests that it may just have been composed for a patron, Elizabeth Power (nee Keating) of Coorheen.