Purpose: The purpose of this study is to develop a European Organisation for Research and Treatment of Cancer Quality of Life Group (EORTC QLG) questionnaire that captures the full range of physical, mental, and social health-related quality of life (HRQOL) issues relevant to disease-free cancer survivors. In this phase III study, we pretested the provisional core questionnaire (QLQ-SURV111) and aimed to identify essential and optional scales. Methods: We pretested the QLQ-SURV111 in 492 cancer survivors from 17 countries with one of 11 cancer diagnoses. We applied the EORTC QLG decision rules and employed factor analysis and item response theory (IRT) analysis to assess and, where necessary, modify the hypothesized questionnaire scales. We calculated correlations between the survivorship scales and the QLQ-C30 summary score and carried out a Delphi survey among healthcare professionals, patient representatives, and cancer researchers to distinguish between essential and optional scales. Results: Fifty-four percent of the sample was male, mean age was 60 years, and, on average, time since completion of treatment was 3.8 years. Eleven items were excluded, resulting in the QLQ-SURV100, with 12 functional and 9 symptom scales, a symptom checklist, 4 single items, and 10 conditional items. The essential survivorship scales consist of 73 items. Conclusions: The QLQ-SURV100 has been developed to assess comprehensively the HRQOL of disease-free cancer survivors. It includes essential and optional scales and will be validated further in an international phase IV study. Implications for Cancer Survivors: The availability of this questionnaire will facilitate a standardized and robust assessment of the HRQOL of disease-free cancer survivors.