Department of Defense acquisition practices are conceptually structured to decrease overhead costs while continuing to improve capabilities and interoperability. These practices mandate build versus buy solutions, with more emphasis on buying pre-built applications. Buying commercial off-the-shelf software -- COTS -- can be a very efficient and effective solution, if the context of the life cycle is considered in all customization decisions. If we are to achieve the expected gains from purchasing software versus building it ourselves, then for the entire life cycle of the product, we cannot allow any modifications. That is easily obtained in many small systems with a little discipline; however, large enterprise resource planning (ERP) solutions will encounter problems if not approached correctly from its initial acquisition phase. This article discusses the issues around COTS and business process reengineering, and improvements we can make to the acquisition process. First, let's examine the reasons a COTS purchase is usually a good choice by taking a look at the total cost of ownership and configuration control. The article addresses the following topics: (1) Total Cost of Ownership Advantage, (2) Configuration and Change Control, (3) Business Process Reengineering, (4) Fine-Tuning the Program Strategy, (5) Incorporating Design for Six Sigma into the Guidebook, and (6) Bringing in Lean Six Sigma.