Deans from 53 colleges of arts, science, and humanities at major U.S. universities provided data about the structure of their colleges. These colleges were studied because structural changes are occurring and baseline data is needed. Forty-two percent of the deans reported that a formal study of reorganization of their colleges had taken place in the last five years. The basic research questions addressed were: what impact does the number of faculty or students (size) have on the number of departments (horizontal differentiation), administrative levels (vertical differentiation), or the proportion of administrators?; and do interdependent faculty networks, such as faculty committees, have a mediating influence on size, structure, and proportions of administration? Propositions developed by Peter Blau in his study of academic and employment security agencies form the conceptual framework for answering these questions. Results of the study (1) confirm the pervasive effects of size on structure; (2) challenge the evidence of prior studies that differentiation offsets the effects of size on the proportion of administrators; and (3) suggest that different forms of interdependent faculty networks have different effects on structure and the proportion of administrators. Implications of the findings for stable or declining enrollments in arts, science, and humanities colleges are discussed. (Author/MSE)