We develop a new approach to endogenizing technological spillovers. We analyze a game in which firms can first invest in cost-reducing R&D, then compete on the human-capital market for their knowledge-bearing employees, and finally enter the product market. If R&D employees change firms, spillovers arise. We show that technological spillovers are most likely when they increase total industry profits. We use this result to show that innovation incentives are usually stronger for endogenous than for exogenous spillovers and that endogenous spillovers may reverse the result that innovation incentives are stronger under quantity competition than under price competition. Finally, we explore the robustness of our results with respect to contractual incompleteness and the number of R&D workers.