This paper describes the rapid, practical, and profitable commercialization path for fuel cells and hydrogen that can be executed by coordinating convergent trends in several industries. The strategy described here relies on existing technologies, can begin immediately, and proceeds in a logical and viable sequence. It has two preconditions: uncompromised ultralight-hybrid vehicles whose inherently high efficiency permits their fuel-cell stacks to rely on conveniently compact onboard tanks of compressed gaseous hydrogen, making onboard liquid-fuel reformers unnecessary and uncompetitive; and integration of fuel-cell market development between vehicles and buildings. This paper provides a specific strategy for transitioning to the widespread use of hydrogen. The authors describe how the careful coordination of fuel-cell commercialization in stationary and transportation applications; the use of small-scale, distributed fueling appliances; and Hypercar vehicles combine to offer leapfrog opportunities for climate protection and the transition to hydrogen.