Abstract
We test the theoretical prediction that inter-firm spillovers must necessarily be large for the profit differential between cooperation and non-cooperation in R and D to be monotone increasing with them. By using the French data from the 2002 Community Innovation Survey, we find that spillovers have a significant positive impact on the likelihood that competitors cooperate horizontally in R and D only if these spillovers exceed a threshold. Both the value and the significance of estimates increase with the flow of information firms report receiving from competitors.