Is mobility of technical personnel a source of R&D spillovers?

Labor mobility is considered to be an important source of knowledge externalities, making it difficult for firms to appropriate returns to research and development (R&D). Interfirm transfers of knowledge embodied in people should be analyzed within a human capital framework. Testing such a framework, I find that the technical staff in R&D-intensive firms pays for the knowledge they accumulate on the job through lower wages early in their career. They later earn a return on these implicit investments through higher wages. This suggests that the potential externalities associated with labor mobility are, at least partially, internalized in the labor market.