In this paper, the explosively increasing demand for energy storage capacitor applications is discussed with particular reference to the various special characteristics required and how they affect the cost, mechanical configuration, circuitry, and protection requirements. Of particular importance at this time, there is included a discussion of means of accomplishing lower inductance and "Q" factor improvement over conventional design. A brief discussion of capacitor fundamentals contributing to the control of discharge waves is presented to illustrate the need for precise determination of circuit characteristics and electrical parameters. Several application problems are discussed, illustrating all of the factors pertinent to the design requirements, and how to obtain them. Since most of these installations represent considerable investment and frequently the need for high reliability, means for protection both against voltage overshoot and isolation in the event of unit failure is also discussed. Thus, the information presented establishes the criteria for selection of large banks of capacitors under the most favorable economic and technical comditions, along with an assurance of reliable performance without excessive unused safety factor dollars.