Purpose: Most patients, providers, and payers make decisions about cancer hospitals without any objective data regarding quality or outcomes. We developed two online resources allowing users to search and compare timely data regarding hospital cancer surgery volumes. Methods: Hospital cancer surgery volumes for all California hospitals were calculated using ICD-9 coded hospital discharge summary data. Cancer surgeries included (bladder, brain, breast, colon, esophagus, liver, lung, pancreas, prostate, rectum, and stomach) were selected on the basis of a rigorous literature review to confirm sufficient evidence of a positive association between volume and mortality. The literature could not identify threshold numbers of surgeries associated with better or worse outcomes. A multidisciplinary working group oversaw the project and ensured sound methodology. Results: In California in 2014, about 60% of surgeries were performed at top-quintile-volume hospitals, but the per-hospital median numbers of surgeries for esophageal, pancreatic, stomach, liver, or bladder cancer surgeries were four or fewer. At least 670 patients received cancer surgery at hospitals that performed only one or two surgeries for a particular cancer type; 72% of those patients lived within 50 miles of a topquintile-volume hospital. Conclusion: There is clear potential for more readily available information about hospital volumes to help patient, providers, and payers choose cancer surgery hospitals. Our successful public reporting of hospital volumes in California represents an important first step toward making publicly available even more provider-specific data regarding cancer care quality, costs, and outcomes, so those data can inform decision-making and encourage quality improvement.