This paper summarizes the results of a series of case studies of utilities. The analysis reported is designed to illustrate and integrate the various issues that surround the potential capacity of the existing and planned electric generating capital stock. The study grew out of general policy concerns over the current lack of capital formation in the electric utility industry and the implications for electricity supply if demand were to increase at a rapid rate. The focus of the study, therefore, is on the current stock, its potential performance over time and how that capacity might be enhanced. In addition, potential new capacity and retirements are considered, as well as the more efficient use of existing capacity through pooling.