This dissertation research uses theory, methods and findings from sociology of professions and science studies to examine academic economics in the U.S. during the 1970s and 1980s. At this time economics was focusing more and more on complex mathematical techniques and on models of free markets. This was despite protests - often coming from high-ranking mathematical economists themselves - that academic work was becoming increasingly unrealistic. The research claims that this state of affairs can be understood by considering the changing relationship between academic economists and economists pursuing careers in more applied fields. Academics pursued more and more abstract theories because they saw themselves as a scientific elite providing the correct knowledge behind all effective work going on in the other fields. Ironically however, they were able to do this only because the more applied fields in fact were becoming increasingly separated from academia and were relying more and more on their own ideas and ways of doing things. Evidence supporting this interpretation will be looked for in the changing patterns of employment of economists across the different fields, and in the statements of economists themselves - both academic and applied - concerning what they do and what they see as being the role of academic theories. Data for the investigations is of four types: existing statistics on patterns of employment; accounts of careers including biographies and listings in handbooks of the American Economic Association; written evidence of the attitudes of academic economists; and original interviews of economists in Chicago and Washington, DC, concentrating on those in non-academic career fields.