This book presents the theory of capital utilization, a discussion of the econometrics of capital utilization, and econometric tests of the theory using international data. Capital utilization, defined as the proportion of time that capital is working productively, is mainly affected by shift-working. Capital utilization is an important economic variable that has received serious attention from economists only since the mid-1960sIn the first part, the authors provide a synthesis of current knowledge, combining a consistent statement of existing theory with some major extensions. In the second part, they turn to the econometrics, first discussing the appropriate methodology and then testing the theory on data from several countries. This empirical work is considerably more sophisticated than previous studies on this topic. Having established the theory and tested it, they move on to consider policy, the relationship between capital utilization and economic growth, and the place of shift-work in the dual economy.