An empirical analysis of Japanese government-sponsored R&D consortia involving 213 firms over 13 years shows that the diversity of a consortium is associated with greater R&D expenditure by participating firms. Diversity is alternatively measured by the Montgomery [1982] index, based on 3-digit SIC codes, and Branstetter and Sakakibara’s [1998] modification of the Jaffe [1986] patent portfolio based index.