Endogenous-growth theory suggests that technological change tends to reinforce the position of the leading nations. Yet sometimes this leadership role shifts. The authors suggest a mechanism that explains this pattern of 'leapfrogging' as a response to occasional major changes in technology. When such a change occurs, the new technology does not initially seem to be an improvement for leading nations, given their extensive experience with older technologies. Lagging nations have less experience; the new technique allows them to use their lower wages to enter the market. If the new technique proves more productive than the old, leapfrogging of leadership occurs.