This is a story about the development of public relations (PR) in the mid-20th century, told through the work of Edward L. Bernays. Bernays, widely considered a “father of public relations,” played a significant role in the formation of PR, not only through his campaigns but also his articles and books on what PR is and how to do it well. In the introduction, I trace the development of PR from the turn of the 20th century to the interwar period. The thesis turn turns to the industry’s expansion in the early post-WWII era, when the economic and cultural impacts of the war made PR newly relevant to corporate practice. The engineering of consent, a theory of persuasion that Bernays first articulated in an essay in 1947, was part of a wider process of defining the rapidly growing profession during this period. In the article, which he later adapted into a book of essays in 1955, he outlined the methodological and ethical approaches PR counsels should take to engineer the consent of the masses for “sound social ends.” Chapter 2 uses the engineering of consent as a lens through which to understand public relations and mass persuasion in a period when PR was becoming more popular than ever before. How does the engineering of consent function, and how does it justify itself? What critiques does the theory try to answer, and how did PR’s critics respond to it? Chapters 3 and 4 will examine the engineering of consent in practice through two case studies: Bernays’ work for United Fruit Company (~1940 - 1959) and for Mack Trucks, Inc. (1949 - ~1952). In these chapters, I explore the extent to which Bernays implemented the professional and ethical guidelines he advocated in his texts, and whether he achieved his objectives. I show that, overall, the engineering of consent explains Bernays’ methods well, but that he failed to meet his ethical ideals in significant ways. Furthermore, the ethics of consent engineering are defined broadly enough to permit a wide range of misleading and/or harmful conduct. I conclude by discussing the contemporary manifestations of what I call the “engineering of consent mindset,” which treats the public as subjects to be researched, understood, and manipulated for the benefit of a private entity.