We develop a tractable dynamic model of productivity growth and technology spillovers that is consistent with the emergence of real world empirical productivity distributions. Firms can improve productivity by engaging in in-house R\&D, or alternatively, by trying to imitate other firms'...

We construct and estimate a unified model combining three of the main sources of cross-country income disparities: differences in factor endowments, barriers to technology adoption and the inappropriateness of frontier technologies to local conditions. The key components are different types of...