This paper explores Max Weber's attempt to redefine the division of labour between abstract economic theory and economic sociology. Weber's main aim was to establish economic sociology as the center of an economic science while abstract economic theory was seen as one heuristic tool among others used in the analysis of social reality. The reception of Weber's analysis of the proper division of labour between these to branches of economics is analysed focusing on the reception of his thesis by von Mises, Schumpeter and Parsons. The main conclusion is that neither economists nor sociologist have found Weber's contribution worth a closer look. The result is that Weber's contribution never has found its way into the methodological discussions in economics as well as into economic sociology. Introduction: Some unresolved issues in economic sociology. Max Weber's contribution to the Methodensstreit in German Economics at the beginning of the century was an attempt to define the proper role for economic sociology (social-economics) and for abstract economic theory in economic analysis. What makes Weber's contribution interesting from the perspective of recent economic sociology is that he argued that economic sociology should constitute the core of economic analysis while the role of abstract economic theory should be a "heuristic tool", among others. The relevance of Weber's contribution is that although economic sociology has shown remarkable results during the last decade, as stressed by Swedberg (1997), some of the most fundamental questions concerning economic sociology as a scientific research tradition seems to have received much too little attention in recent debates. Among these fundamental questions, two crucial questions, are of special importance: 1. What constitutes the core of economic sociology? Is economic sociology constituted by its research subject, by its method or by its choice of (a sociological) perspective? 2. What is the relation between economic sociology and abstract economic theory? Are these two traditions competing perspectives focusing on the same research area? Are they instead complementary perspectives with a different focus and definition of their respective research object? Abstract economic theory has always constituted the main alternative and the main challenge to economic sociology. The relevance of exploring Weber's contribution on this issues is that he has presented the most controversial standpoint on the division of labour between economic sociology and abstract economic theory (Gislain & Steiner, 1995). In this paper I will explore the basic argument presented by Weber on the division of labour between economic sociology and abstract economic theory. Further, I discuss the reception of Weber's contribution made by the most important earlier economists and sociologists: Schumpeter, Mises and Parsons. Last, I discuss the relevance of Weber's contribution in light of recent issues in economic theory and economic sociology.