Timely identification of patient deterioration can prompt intervention and prevent the escalation of care and unplanned intensive care admissions. However, both personal experience and professional literature reveals that staff nurses in the acute care setting may not notice subtle signs of patient deterioration or may be reluctant to activate the rapid response system. To overcome these barriers, a proactive rapid response system with early warning signs was created and studied. Using a quasi-experimental design, data were collected from two medical-surgical nursing units at one large tertiary medical center over a 6-month period. One unit used the new rapid response system and early warning sign criteria with real-time data entry and trigger activation. A second unit served as the control and relied on the nurse for rapid response system activation. Findings revealed that the use of the newly developed rapid response system demonstrated significantly greater sensitivity to subtle signs of patient deterioration and prompted early evaluation and intervention.