Learning and Experience Curves measure increased productivity resulting from on-the-job training of apprentices in the former case and from highly repetitious work in the latter case. Both concepts are applicable to problems of forecasting manpower requirements, accelerations, delays and extra work with emphasis on costs and economy. Experience Curves are developed for Individual Times (IT) and Cumulative Average Times (CAT). These two families of curves are subsequently related to each other. Loss of Efficiency due to delays and interruptions is discussed and quantified. Appendices treat the exponential, or six-tenths rule, as well as economic lot size. Ten solved problems further illustrate the wide application of this technique; indeed, these problems cannot be readily solved otherwise. Tables and graphs are included to facilitate the solution of problems.