ABSTRACTSince Fiscal Year 1979, Congress has required thai Defense Department budgets provide the relationship between resources and readiness. This required that the Navy establish a measure of material readiness. Operational availability, or Ao, became the measure of material readiness in 1981. In March of 1981, CNO approved the Availability Centered Inventory Model (ACIM) as the Navy spares optimization model for use in shipboard weapon systems and equipment applications. The early 1980s terminology of “Sparing to Availability” is currently termed “Readiness Based Sparing.” CNO mandated in August 1986, the universal application of readiness based sparing techniques to all non‐nuclear ACAT I, II and III acquisition programs.RBS is not just a model into which data is input and an allowance of spare parts is printed out. RBS is a process that requires consistent and continuous integration and correlation of spares data to total system data, operating parameters and requirements. Support requirements must be determined in conjunction with the total weapon system, and material readiness, measure of effectiveness and performance should be assessed against that same measure. Traditional measures of supply system effectiveness are only partial input data to the ultimate requirement of weapon system material readiness.The Readiness Based Sparing Process is a disciplined integration of design, configuration management, maintenance, and logistics support. RBS is system specific. Therefore, all data that is input to an RBS model must be system application specific. Today's data collection systems, and consequently the budget and execution processes, are not oriented to specific weapon system management. Consequently, the current and ongoing agenda in the implementation and institutionalization of Readiness Based Sparing – The Process, is directed towards the integration of logistics data bases, and the data within those data bases, to a weapon system management orientation.