U.S. Government procurement spending exceeds $500B annually. A request for proposal is one of the more common forms of solicitation, and source selection (SS) is the process for evaluating proposals submitted by contractors. The U.S. Department of Defense and the Army promulgate manuals and supplements that direct the SS process within those organizations. Those publications identify “trade-offs” as a preferred method for conducting a SS, and encourage the use of this process “when it may be in the best interest of the Government to consider award to other than the lowest-price offeror.” Under this process, cost and non-cost factors are evaluated and the contract is awarded to the offeror proposing the combination of factors that represents the best value based on the evaluation criteria. This case study will describe how a trade-off, or structured decision, process was used to support a U.S. Army SS by thoroughly evaluating multiple vendors and their proposals of a major subsystem for a major defense acquisition program. The purpose of this case study is not to focus solely on how to accomplish a trade-off, or execute a SS, but rather to share lessons-learned about how to address special situations encountered during a SS trade-off.