This paper proposes the use of a new Systems Readiness Level (SRL) scale for managing system development and for making effective and efficient decisions during the defense acquisition process. This scale incorporates both the current Technology Readiness Level (TRL) of the Department of Defense (DoD) and the concept of an Integration Readiness Level (IRL) developed by Stevens Institute of Technology. The paper describes the foundations for the SRL and how it is formulated; it also demonstrates the SRL's application within the defense acquisition process using a sample case with notional readiness values.