We study how the inventive capability of a firm conditions its participation in a division of innovative labor. Capable firms are, by definition, able to invent; for them, external inventions substitute for their own R&D. However, external knowledge is an input into internal invention, and thus,...

Using data from the Federal Trade Commission's Line of Business Program and survey measures of technological opportunity and appropriability conditions, this paper finds that overall firm size has a very small, statistically in- significant effect on business unit R & D intensity when either...