We provide causal evidence on the effects of language barriers on the speed and extent of knowledge diffusion by exploiting the introduction of pre-grant publications in the US. Language barriers account for almost half the diffusion lag of Japan-originating knowledge to US-based inventors, relative to Japan-based inventors. This acceleration is significant only for firms with low appropriation advantage in translation (small R&D scale, or little involvement in the Japanese market), and is larger for the diffusion of high-quality inventions, suggesting difficulties of quality-targeted translation. Thus, pregrant publication provides a significant public good for cumulative innovation through accelerated access to translated foreign patents.
