The Zero Acceptance of Pain (ZAP) Quality Improvement Project was a multi-site effort to improve the lives of outpatients with cancer pain by enhancing the clinical practice of pain assessment and management. Independent samples of patients completed self-report measures of severity of pain, pain interference, global quality of life, pain treatment satisfaction, general medical treatment satisfaction, pain attitudes, and pain-related medical costs before and after the implementation of ZAP. Results suggested that ZAP decreased the severity of recent pain, decreased interference of pain on daily functioning, and improved satisfaction with pain treatment and attitudes about addiction to opioid medication. Direct medical costs consisting of pain-related hospitalizations, emergency department visits, and physician office visits were greatly reduced. In summary, the findings of this study support the idea that clinic-based efforts to improve the practice of pain management are effective in improving the lives of cancer patients who are experiencing pain.