Flavonoid intake is inversely associated with the incidence of chronic diseases, but the sources of flavonoid intake in free-living U.S. adults have not yet been reported. We tested hypotheses that tea is the major dietary source of flavonoids in U.S. adults; tea consumers differ from those of tea nonconsumers in sociodemographics, health-related behaviors, and dietary and beverage sources of flavonoid intake. We matched the flavonoid contents of the USDA Flavonoid Databases with dietary intake data of adults (n = 8809) included in NHANES of 1999-2002. Only 21.3% of U.S. adults reported drinking tea daily. Daily total flavonoid intake of tea consumers was over 20 times that of tea nonconsumers (697.9 vs. 32.6 mg/d); per capita flavonoid intake from tea was 157 mg/d. Tea consumers are more likely to be older, female, white, and to have higher income than tea nonconsumers (P < 0.001); to have lower nonleisure-time physical activity level (P < 0.01); and to take dietary supplements (P < 0.001) than tea nonconsumers. Intake of flavonols and flavan-3-ols, the major tea flavonoids, differed between the 2 groups (P < 0.01). Other dietary flavonoid sources after tea were citrus juice, wine, and citrus fruits for both tea consumer and nonconsumer groups. For tea nonconsumers, flavonoid intake from wine, fruitades, and fruit drinks was higher than that in tea consumers. Flavonoid intake differs among subgroups, mainly because of the percentage of tea consumers and the prevalence of tea consumption within each subgroup.