This essay relates recent developments in growth theory to problems and ideas that first engaged R. F. Harrod, E. Domar, and their neoclassical successors. The body of 'new growth theory' began by finding special ways to assume that there are constant returns to capital. It is shown that this is...

International productivity comparisons can be built up with micro and macro data. Studies of firms or groups of firms producing similar outputs reveal the deeper causes of differences in productivity across countries. The studies find that such differences often depend on patterns of...

This note contains some general and idiosyncratic reflections on the current state of neoclassical growth theory. It expresses some surprise at the lack of attention both to multi-sector growth models and to multi-country models with trade and capital flows. It also suggests that there might be...