We report on the development and validation of an instrument to assess support and resources for chronic illness management (the Chronic Illness Resources Survey; CIRS). The 64-item full instrument and the 29-item Brief CIRS are based on a social-ecologic model, designed to apply across chronic diseases, and assess support and resources at each of seven levels (e.g., family and friends, physician and health care team, neighborhood/community). A prospective evaluation with 123 patients having heart disease, arthritis, diabetes, and/or COPD revealed that the overall instrument, as well as subscales and the brief instrument, had acceptable internal consistency, moderate to high test-retest reliability, good construct validity, and moderate concurrent and prospective criterion validity. We discuss potential uses of the CIRS for assessment, feedback, tailoring intervention, and evaluation and make recommendations for future research.