This is a commentary on Morris Janowitz’s article, “Military Institutions and Citizenship in Western Societies,” published in February 1976, in Armed Forces & Society, Vol. 2, No. 2, pp. 185–204. In the article, Janowitz links sociopolitical changes to the rise and subsequent fall of mass popular Armies. Military service during the 19th century was an integral part of citizenship. However, in the 1960s, mass militaries based on compulsory service began to transform into smaller volunteer forces “with profound implications for social structure, political power, and nationalism.” In this article, I highlight Janowitz’s analysis of the rise and fall of the mass armed forces. I also discuss the three sets of factors Janowitz used in his analysis: (a) technological and organizational change, (b) a rise in small professional militaries that are unrepresentative of the larger society, and (c) ideological and normative change. I end with a brief discussion on how Morris Janowitz’s legacy helps to shape our understanding of civil–military events that have taken place over the last 50 years.