This paper sketches a new theoretical approach to the study of professions and uses that approach to analyze differences that have emerged between the American and English legal professions since the late nineteenth century. Earlier studies have generally emphasized professional structure and organization while ignoring work and its control. I argue that control of work is central to professional development. Since work is central and since professions compete for it, interprofessional competition is the determining fact in the history of professions. This paper analyzes the work available to the legal profession, the numbers and types of legal personnel available to do that work, and the various competitors contesting it. Studying in detail complaints of unqualified practice in England (1870–1940) and two American states (1910–50), I locate the types of contested work and the competitors involved, using these to explain important aspects of the two legal prof essions today. Throughout, a variety of theoretical concepts are developed and applied to the particular case. One striking discovery is the contrast in competitors; American lawyers' chief competitors were corporations, while British lawyers' chief competitor was the state. I close by evaluating the strengths and weaknesses of the particular methodology here used—the study of conflicts—and suggest alternative methods using the same theoretical framework.