Complementary and alternative medicine (CAM) occupations continue to struggle towards achieving professional status, especially in the form of statutory regulation. Many consider professional status a worthwhile goal for CAM occupations, yet it is a process fraught with tensions. In this paper we present in-depth interview data from the leaders of three CAM groups (naturopaths, traditional Chinese medicine practitioners acupuncturists, and homeopaths) in Ontario, Canada that demonstrate four main strategies used by these groups to professionalize. The strategies discussed are related to how the knowledge base of each group is organised and transmitted. These strategies include: improving educational standards, improving practice standards, engaging in peer-reviewed research and increasing group cohesion. At the core of these strategies is the demarcation of who is qualified to practice, and a signalling to 'outsiders', such as medicine and the government, that practitioners are qualified and legitimate. Across the three groups, the leaders referred to the inclusion of medical science as a basis for distinguishing between 'science' and 'non-science' as well as who should practice and who should not. We highlight how internal battles over the infusion of medical science into the knowledge base are part of the process for establishing legitimacy for the three CAM groups in our study. We end with a brief discussion of the implications of these internal battles over medical science knowledge for the future of CAM groups.