Canada, as one of the three Allied nations collaborating on atomic energy development during the Second World War, had an early start in applying its new knowledge and defining a new profession. Owing to postwar secrecy and distinct national aims for the field, nuclear engineering was shaped uniquely by the Canadian context. Alone among the postwar powers, Canadian exploration of atomic energy eschewed military applications; the occupation emerged within a governmental monopoly; the intellectual content of the discipline was influenced by its early practitioners, administrators, scarce resources, and university niches; and a self-recognized profession coalesced later than did its American and British counterparts. This paper argues that th...