The establishment and growth of Irish-medium education has been central to the revitalisation of the language in Northern Ireland in recent years. Historically, the struggle by the minority of Irish speakers in the region to provide all-Irish schools has been both the goal and the engine of renewal and expansion during a period of community and political conflict. The present paper analyses the growth in the sector from the initial campaign for resources and official recognition of the first all-Irish school in Belfast's Shaw's Road Gaeltacht. It documents the range of sociolinguistic and educational challenges faced by the earliest immersion schools, and the manner in which the response served to mobilise individual speakers and contributed to the emergence of the small but unique urban community of Irish speakers. Among the issues discussed are the early internal conflicts about the merits of independent all-Irish schools (as in the Republic) versus all-Irish units within English-medium schools, and the manner in which an accommodation was gradually achieved between a reluctant Department of Education and the growing immersion sector. This paper deals with a number of other issues that help to define immersion education in Northern Ireland, including differences in the organisation of the sector compared to the Republic and the continuing challenges faced in areas of research, planning and teacher training.