Since 1975 the Army has suffered major reductions in its authorizations for active duty combat service support (CSS) manpower. Today, concerned observers are asking: to what extent have these reductions in CSS compromised Army combat power, and what can be done to correct the deficiency? The purpose of this paper is to suggest a methodology for measuring CSS functions in relation to combat power to better illustrate the weighted importance of CSS. One suggested tool to help in defining CSS objectives and in evaluating CSS effectiveness and costs is the Force Reliability Model at Appendix A. Hypothetical data are used to illustrate the methodology, but the formulas are applicable to factual data.