A common cause strategy is an essential conceptual approach for understanding variation and what might be contributing to it as well as informing the redesign of processes and systems to reduce inappropriate and unintended variation. This article describes what a common cause strategy for improvement is and the steps required for this approach. We describe a practical example of how this is applied in a real-life situation. The first step in a common cause strategy is to look more deeply at this common cause variation to see whether special causes can be exposed using stratification. The second step is to seek to understand existing variation by understanding the processes and systems leading to the observed problem. Finally there is a need to redesign processes to reduce inappropriate and unintended variation in any agreed measures by agreeing and incorporating critical inputs and outputs from a provider-patient perspective in the context of systems thinking.