The original school was built in the 1840's and remained in use until the present school was built in 1957. The old building which is close to the present school is a building of strong architectural quality. The new school is a typical example of a two teacher school of the period. Mr. Patrick Haran who taught here from 1969 to 1979 laid out the grounds of the school in a most attractive way. In 1980 Iniscealtra received first place in the All Ireland National School Gardens Competition.
A major extension and refurbishment of the existing school was completed in 2000. Two new classrooms replaced temporary structures and a staff room, new toilets and a storage room were added. All the rooms in the original building received a complete overhaul. This work came about as a result of a major campaign over the previous few years. It would not have come about without the exceptional support shown by the parents of the children in the school and the leadership given by the Irish National Teachers Organisation.
The school takes its name from the island of Iniscealtra, known locally as Holy Island. A monastery was founded here in the sixth century by St. Colm and today there are the ruins of seven churches and a well preserved round tower on the island.