The findings in this report are subject to at least six limitations. First, BRFSS and YRBS data are self-reported. Among adults, alcohol consumption generally, and excessive drinking in particular, are underreported in surveys because of recall, social desirability, and nonresponse bias.9 A recent study found that BRFSS identifies only 22% to 32% of presumed alcohol consumption in states based on alcohol sales.10 Second, an increasing proportion of youths and young adults aged 18-34 years use cellular telephones exclusively11; therefore, landline surveys of persons in this age group might not be representative of this population. Third, the results of the cellular telephone survey were unweighted, but results of the landline survey were weighted to represent the U.S. adult population. However, the distribution of cellular telephone respondents by various demographic characteristics (e.g., sex and race/ethnicity) was quite similar to the composition of the general population, and the cellular telephone data were age-adjusted to the 2000 U.S. Census standard population. Fourth, response rates for both the landline and cellular telephone BRFSS were low, which increases the risk for response bias. Fifth, YRBS defines binge drinking for boys and girls as five or more drinks within a couple of hours, and the prevalence of binge drinking among girls would likely have been higher if it were defined using a four-drink threshold, consistent with national recommendations. Finally, YRBS data apply only to youths who attend school, and therefore are not representative of all persons in this age group. Nationwide, in 2007, of persons aged 16-17 years, approximately 4% were not enrolled in a high school program and had not completed high school.#