In Chapter 10, we interrogate the relation between scale and professionalism, which we define as meaning that important tasks are delegated through a rational division of labor to individuals with extensive training and experience, who are recruited and promoted in a meritocratic fashion, who view their job as a full-time career, and whose positions are amply staffed and remunerated. We argue that scale fosters professionalism because it produces higher (human) capital, and because it amplifies the complexity of governance. Subsequently, we examine the relationship empirically by sequentially looking at legislatures, bureaucracies, the education of public officials, the salary of public officials, and the number of voluntary associations. We find that increases in scale are associated with a growth of legislative and bureaucratic professionalism and capacity, higher levels of education and higher salaries of public officials, and a greater number of voluntary associations. Extant studies as well as our own analyses therefore suggest that scale is positively correlated with professionalism. These results are summarized in a short conclusion.