BACKGROUND: Interest in monitoring the quality of health care in the United States has increased in recent years. However, the policy objectives associated with collecting this information are constrained by the limited availability of timely and relevant data at a reasonable cost. Online data-collection technologies hold the promise of gathering data directly and inexpensively from large, representative samples of patients and consumers. These new information technologies also permit efficient, real-time assessment in such areas as health status, access to care, and other aspects of the care experience that impact health outcomes. OBJECTIVE: This study investigates the feasibility, validity, and generalizability of consumer online surveys to measure key aspects of health care quality in the United States. METHODS: Surveys about the health and health care experiences of a general adult population and of adults with diabetes were administered online and by telephone. The online survey drew from a sample frame of nearly 1 million consumers and used a single e-mail notification. The random-digit-dial methodology included 6 follow-up calls. Results from the online sample were compared to the telephone sample and to national benchmark data. RESULTS: Survey responses about quality of care collected using online and telephone methods were commensurate once they were weighted to represent the demographic distribution of the 2000 United States Census. Expected variations in health and health care quality across demographic and socioeconomic groups were largely observed, as were hypothesized associations among quality indicators and other variables. Fewer individuals were required to be contacted to achieve target sample sizes using online versus telephone methods. Neither method yielded representative cohorts of nonwhite individuals. CONCLUSIONS: Conclusions about the level and variations in health care quality in the United States are similar using data collected in this study compared to data collected using other telephone-based survey methods. As is typical for national telephone surveys conducted by the National Center for Health Statistics, stratified sampling and weighting of survey responses is necessary for results to be generalizable. Online methods are more appropriate for understanding health care quality than for conducting epidemiologic assessments of health in the United States.