This book proposes a new way to approach comparative international development by focusing on time and timing in economic and social development. The UK industrialized over two centuries, and then started to de-industrialize in the late 1960s. Today, the most rapid developers experience aspects of industrialization and de-industrialization simultaneously. It is no longer clear that industrialization offers the path of growth it once did; industrialization has become ‘thin.’ Demographic and social challenges that earlier developers faced sequentially now come at the same time. Rapid growers experience compression most acutely, but the spatial and temporal fusing of past and present is widespread, affecting high-, middle-, and lower-income countries alike.