This article compares findings from two surveys of Chicago lawyers, the first conducted in 1975 and the second in 1995. The earlier study indicated that the Chicago bar was then divided into two broad sectors or “hemispheres,” one serving large corporations and similar organizations and the other serving individuals and small businesses. Analyses of the structure of co-practice of the fields of law indicate that the hemispheres are now less distinct. The fields are less tightly connected and less clearly organized—they became more highly specialized during the intervening 20 years and are now organized in smaller clusters. Clear indications of continuing separation of work by client type remain, however. Estimates of the amount of lawyers' time devoted to each field in 1975 and 1995 indicate that corporate practice fields now consume a larger share of Chicago lawyers' attention, while fields such as probate receive a declining percentage. Growth is most pronounced in the litigation fields, especially in business litigation. The organizational contexts within which law is practiced both reflect and contribute to these changes. The scale of those organizations has increased greatly, and the allocation of work within them has been divided along substantive, doctrinal lines. As a result, there is a greater disaggregation of work and workgroups within the profession today.