The PDCA (plan, do, check, act) cycle has been around for several decades and remains a popular tool to improve quality. It also serves as an excellent road map for performing Lean in an enterprise both as an overall framework and also as a specific tool to improve a process, procedure, or operation. This chapter presents the PDCA cycle from the perspective of the former. In some places, PDSA rather than PDCA is used, meaning plan, do, study, act.