One of Achill's most famous historical sites is that of the Achill Mission or 'the Colony' at Dugort. In 1831 the Protestant Reverend Edward Nangle founded a proselytising mission at Dugort. The Mission included schools, cottages, an orphanage, a small hospital and a hotel (now the Slievemore Hotel).

The 'Colony' was very successful for a time and regularly produced a newspaper called the 'Achill Missionary Herald'. The Reverend Nangle expanded his mission into Mweelin, where a 'university' was built. In this building, Bible readers were trained to teach the bible in Irish.

The Achill Mission began to decline slowly and finally closed in the 1880's. Edward Nangle died in 1883.