227 Background: The objective of this work was to develop a reliable and valid survey measuring aspects of cancer care important to patients to be used in both inpatient and outpatient settings, and that allows comparisons of patient experiences across treatment centers and treatment modalities (medical oncology, radiation, surgery). Other objectives included testing various modes of data collection and developing a standardized sampling methodology based on ICD diagnosis and procedure codes. Methods: We conducted focus groups with patients who had received cancer treatment and with family members of cancer patients. We convened a panel of experts representing quality improvement, oncology, shared decision-making, patient safety, and patient advocacy to obtain feedback on the development of the survey. We interviewed stakeholder groups representing oncology associations to obtain feedback on focal provider, attribution and sampling. We then conducted a field test of the survey among six cancer centers around the country, conducted psychometric analyses, revised the survey, conducted a second field test among four community oncology practices in CA, re-analyzed the data, and finalized the survey. Results: Final survey content was determined using results of the formative research, psychometric analyses, and input from the CAHPS Consortium. The core survey includes 56 questions, 23 of which map to eight composites: Provider Communication, Enabling Patient Self-management, Team Available to Provide Information, Access to Care, Care Coordination, and Office Staff. Supplemental item sets include seven items assessing Shared Decision Making, four items measuring Keeping Patients Informed, and two additional Access to Care items. Mail-only, mail-telephone mixed-mode, and web-mail mixed-mode are recommended methods of data collection. The survey and all recruiting materials are available in English and Spanish. Conclusions: The CAHPS Cancer Care Survey is a rigorously developed, well-tested, reliable and valid survey of patient experiences with their cancer care. The survey and supporting materials are available free of charge on the CAHPS website (www.ahrq.gov/cahps).