In this study the problem may be stated as follows: Can Dynamic Programming be used to design a leacher, and if so, how do the results compare to the results obtained by using conventional Chemical Engineering techniques as represented by McCabe-Smith? Secondary data for the study were obtained from the literature, laboratory analyses made by a manufacturing firm in San Diego, California, and published utility rates. Primary data were obtained from laboratory tests and various business firms located in San Diego County. The procedure of the study was to design a leacher of N stages by the McCabe-Smith technique and by the Dynamic Programming technique, utilizing the data gathered. The two design techniques were compared by cost criteria: cost of design, construction, and operation. The findings of the study were that (1) the leachers designed by the McCabe-Smith Constant Underflow method and the Dynamic Programming method were identical except for efficiencies, and (2) the leacher from the McCabe-Smith Variable Underflow method was comparably efficient but required five stages instead of two stages each for the other leachers. The cost of design by all methods was the same. The system designed using the McCabe-Smith Variable Underflow method cost over twice as much to construct and about 10 percent more to operate than the systems from the Dynamic Programming and McCabe-Smith Constant Underflow methods. Conclusions drawn from the study were as follows. The Dynamic Programming technique could be used to design a leacher optimally and these results did not vary significantly from those obtained by conventional Chemical Engineering practice. The Industrial Manager acquired another tool in Dynamic Programming for deciding how to allocate capital and materials in a multistage decision process. The Dynamic Programming technique required framing the problem so that an optimal solution was sought. The optimal solution was to build a two-stage leacher of 2,940 gallons per stage.