We propose a theory of economic development in which technology adopti
on and barriers to such adoptions are the focus. The size of these bar
riers differs across countries and time. The larger these barriers, th
e greater the investment a firm must make to adopt a more advanced tec
hnology. The model is calibrated to the U.S. balanced growth observati
ons and the postwar Japanese development miracle. For this calibrated
structure we find that the disparity in technology adoption barriers n
eeded to account for the huge observed income disparity across countri
es is not implausibly large.