In the national education policy decision-making, public participation is becoming a burgeoning alternative to professionalism, which is often criticised for its elitist and undemocratic features. However, it is necessary to clarify the concepts and relevant issues first before hastily establishing the binary relationship between professionalism and public participation. This paper, relying on realist methodology, conducted literature review. It was found that the concept of professionalism kept evolving. More specifically, this study compared the concept of professionalism in the 20th century with that in the 21th century. The two issues related to professionalism were: 1) it was unclear who were educationalists; and 2) It was difficult for educationalists to act as professionals. Concerning the concept of public participation, this study investigated its legal basis, academic conceptualisation, its quality, its prerequisites and the model of deliberative public consultation. The issues of public participation were: 1) the individual characteristics of citizens were obscured by a good cause of the public participation; 2) the aim of public participation was ambiguous. Based on this analysis, this article argued for the complimentary relationship between professionalism and public participation. To achieve this, this research suggested the direction and the realist methodology appropriate to the national education policy decision-making in South Korea.