Q: I’ve been asked recently, are harps permitted at Mass? They certainly cannot replace the organ and piano, and it is a stringed instrument so my guess is yes. If it is permitted, how should it be used and not abused at Mass?
A: You’re fine with harps. See Sacrosanctum Concilium 120 and Musicam Sacram 62.
I don’t know of any restrictions from our conference of bishops.
A good harpist could accompany singing or play a solo of sacred music.