Mental deficiency nursing evolved as a distinct, yet little known field of nursing education and practice in several countries during the twentieth century. In Canada it became a separate area of nursing in only one of its provinces, Alberta, and it was tied to one large institution, called the Provincial Training School for the care of developmentally disabled children and, eventually, also adults. This paper contributes to the history of mental deficiency nursing, currently called intellectual disability nursing, an existing specialty actively practiced in the UK and Ireland for example. Alberta’s program was established in 1933 and continued until 1973. I examine this history through the lens of three mental deficiency nurses’ experiences of their education and work at the institution shared in an oral history interview. These nurses worked in the institution in the period after the Second World War. Their stories provide a unique perspective on a field of nursing work and education that grew increasingly controversial during the latter half of the 20th century when public debate arose over the institutionalization of people with developmental disability. Moreover, the institution’s entanglement within an active eugenics policy and practice maintained in the province of Alberta until 1972 added to the controversy. Their stories provide insight in the perceptions and emotions of mental deficiency nurses, experienced and remembered some sixty years later in an interview. I examine how the nurses took up this work and how their professional identity was depicted and changed, especially as public debate arose from the 1970s onward. The stories provide a unique micro-historical lens to explore larger social and cultural tensions over eugenics, disability, care and dependency, and over mental deficiency nurses’ work. Résumé Les soins infirmiers en déficience mentale ont évolué en tant que branche distincte, mais méconnue, de la formation et la pratique infirmière dans plusieurs pays au cours du 20e siècle. Au Canada, ils sont devenus une discipline séparée des soins infirmiers dans une seule province, en Alberta, et ils ont été liés à une grande institution nommée la Provincial Training School pour les soins aux enfants ayant des déficiences intellectuelles et, éventuellement, aux adultes. Cet article contribue à l’histoire des soins infirmiers en déficience mentale, à notre époque appelés soins infirmiers en déficience intellectuelle, une spécialité existante et activement pratiquée, par exemple, au Royaume-Uni et en Irlande. Le programme en Alberta a été établi en 1933 et s’est poursuivi jusqu’en 1973.