The focus of this article is on the professional development of teachers in Irish-medium education in Northern Ireland, with attitudinal information collected from staff in Irish-medium schools on the range and quality of the professional in-service education and training (INSET) and support opportunities they have experienced. Fieldwork for the research was carried out between October and November 2002. In total, 74% of teachers from Irish-medium primary schools, and 77% of teachers from Irish-medium post-primary schools completed and returned questionnaires. The questionnaire looked primarily at demographic details, such as gender, age, year of class, years teaching, responsibilities held, qualifications, etc., with an emphasis on determining: the in-service courses attended and their relevance, benefits and quality; in-service courses which should be offered; in-service courses to be delivered in the Irish language; support offered for attending in-service courses; and problems experienced when wishing to attend in-service courses. (Contains 8 figures.)