Extending and expanding Geiger and Feller’s analysis of increasing dispersion in R&D expenditures during the 1980s, the paper analyzes publication and citation counts as well as R&D expenditures for 194 top producers using Web of Science data. We find high and stable levels of inequality in the 1990s and 2000s, combined with robust growth both in the system and on individual campuses, considerable opportunities for short-range mobility and very limited opportunities for long-range mobility. Initial investments in research, private control, and (...) the capacity of wealthy institutions to attract productive faculty are associated with high levels of scientific output. New entrants to the system and those that leave the system are both clustered near the bottom of the hierarchy. (shrink)