LABOR PRODUCTIVITY in the private business sector grew at an annual rate of 1 percent from 1973 to 1978, about one-third of its rate of growth from 1948 to 1965. The effects of this slowdown were both substantially reduced economic growth and higher prices. A comprehensive analysis of recent economic growth has been made by Edward F. Denison, who examined the effects of regulation on growth in a framework that assesses the contributions from various potential causal factors. Our approach is different from his in several respects, depending primarily on the definition of output and the measurement of capital input. Several other studies have focused on particular issues in the productivity puzzle, such as analyses of the effects of capital formation, energy, labor force composition, and intersectoral shifts of labor.