[1] Its mission statement is "To produce publications and resources in support of Irish-medium education and of the use of Irish in general.

Its purpose was to ensure a supply of textbooks and general books which would be required to implement the policy of reviving the Irish language.

[1] Until well into the 1960s, An Gúm also published musical scores, some of them expressly for educational purposes at Irish schools.

During the 1930s and 1940s, this was one of the few publishing opportunities for contemporary Irish composers including Rhoda Coghill, Aloys Fleischmann, Redmond Friel, Carl Hardebeck, John F. Larchet and Éamon Ó Gallchobhair.

[9] The syllabus is specifically, but not exclusively, designed for use in Gaeltacht schools and gaelscoileanna, where teaching takes place through the medium of the Irish language.

Séideán Sí is a joint initiative of Foras na Gaeilge and the Department of Education.