This paper uses confidential microdata from the Census of Services to examine law firms' field boundaries. We find that the share of lawyers working in fieldspecialized firms increases as market size increases and lawyers field-specialize, indicating that transaction costs between lawyers, and not just complementarities in clients’ demands, affect law firms’ field boundaries. Moreover, we find that this pattern is mainly true when looking at fields where lawyers are involved in dispute resolution rather than in structuring transactions. We then analyze which combinations of specialists tend to work in the same firm and which tend not to do so. We relate our results to theories of law firms’ boundaries from the organization economics literature. Our evidence leads us to eliminate risk-sharing as an important determinant of firms’ field boundaries and narrows the set of possible monitoring or knowledge sharing explanations.

This paper examines hierarchies’ role in the organization of human-capital-intensive production We develop an equilibrium model of hierarchical organization, then provide empirical evidence using confidential data on thousands of law offices from the 1992 Census of Services. We show how the equilibrium assignment of individuals to hierarchical positions varies with the degree to which their human capital is field-specialized, then show how this equilibrium changes with the extent of the market. When the extent of the market increases, individuals’ knowledge becomes narrower, but deeper. Managerial leverage, the number of workers per manager, optimally increases to exploit this depth. We find empirical evidence consistent with a central proposition of the model: the share of lawyers that work in hierarchies and the ratio of associates to partners increases as market size increases and lawyers field-specialize. Other results provide evidence against alternative interpretations that emphasize unobserved differences in the distribution of demand or “firm size effects,” and lend additional support to the view that a role hierarchies play in legal services is to help exploit increasing returns associated with the utilization of human capital.

This paper presents theory and evidence on horizontal industry structure. At issue is the question: what makes industries necessarily fragmented? The theoretical model examines trade-offs associated with affiliation and integration, and how they are affected by the contracting environment. I show how contractual incompleteness can lead industries to be necessarily fragmented. I also show that contractual improvements will tend to lead to a greater concentration of brands, but whether they lead industries to be more or less concentrated depends on what becomes contractible. I then discuss the propositions generated by the model through a series of case study examples.