I. The nature of optimum size, 569. — II. Problems in estimating optimum size, 570. — III. Previous techniques for the estimation of optimum size, 572. — IV. The survivor technique, 572. — V. Applying the technique, 574. — VI. An investigation of the relationship between optimum plant size and various economic variables, 582. — VII. Summary and conclusions, 596. — Appendix I. Optimum size in 89 American manufacturing industries, 598. — Appendix II. Four possible movements in the distribution of plants, 603. — Appendix III. Measurement of the independent variables, 605.