The modified early warning system (MEWS) is a scoring rubric used to detect the earliest signs of a change in a patient's condition. This mixed-methods study used pre- and postintervention data to describe the impact of the MEWS on the frequency of rapid response system activations and cardiopulmonary arrests among patients admitted to medical-surgical units. Focus groups of nursing staff provided insight into the factors that influence how nurses use the MEWS at the bedside as a framework to identify, intervene, and manage patients in need of an advanced level of care.