Deertrees Theatre is a performing arts center located in Harrison, Maine, United States. The theatre was founded by the distinguished opera director and singing coach Enrica Clay Dillon in 1936 and is now owned and operated by the non-profit Deertrees Foundation. As home to the Deertrees Theatre Festival, the Sebago-Long Lake Music Festival, the BackStage Gallery, and the Salt Lick Cafe, Deertrees is one of the most active summer theatres in the Northeast. Listed on the National Register of Historic Places and the Maine Register of Historic Places, it is sanctioned by the Actors' Equity Association as "a small professional house."