Two trends in the use of quantitative methods of evaluating libraries that have evolved from general systems analysis are discussed in this literature review. The cost effectiveness approach is aimed at discovering new, improved procedures and devices for providing library services; such alternatives make it possible to evaluate how efficiently a library is using resources to provide the services that it does. The cost-benefit analysis approach develops standards and criteria for determining how well the library services provided satisfy the needs and desires of the users and funders of the library. These trends both lead to complex, detailed analysis, requiring sophisticated research techniques. (Author/MBR)