An historiographical study of documentary records for the period 1919-70 in Britain and Ireland was undertaken to analyse the role played by Irish Division psychiatrists of the Royal Medico-Psychological Association, nursing regulatory bodies, the Irish State and specific Catholic religious orders in the development of intellectual disability nursing. Primary and secondary sources were examined to construct a narrative chronology. A postcolonial and social historical framework was employed to provide a means of narrating the development of a new nursing workforce. Irish government funding for rapid expansion of specialised care and residential schools by Catholic religious orders between 1935-60 led to the introduction of 37 RMPA-trained mental deficiency nurses, during the 1940s. The General Nursing Council for Ireland was not involved in such training and opposed medical involvement in nursing education. From 1960, Ireland developed a nursing workforce despite alternative social care models that were emerging elsewhere. Divergent conceptions of training versus treatment between religious orders and psychiatrists led to tensions in syllabus development with an enduring impact. Intellectual disability nursing in Ireland was delayed by postcolonial opposition to medical control of care for people with intellectual disabilities, on cost grounds and by lack of a legislative imperative.