Underage drinkers typically have not developed regular patterns of drinking and so are likely to exhibit situational variation in alcohol intake, including binge drinking. Information about such variation is not well captured by quantity/frequency (QF) measures, which require that drinkers blend information over time to derive a representative estimate of "typical" drinking. The Timeline Followback (TLFB) method is designed to retrospectively capture situational variations in drinking during a specific period of time. We compared our newly-developed Self-administered TLFB (STLFB) measure to a QF measure for reporting alcohol intake. Our sample of 429 (men=204; women=225) underage (i.e., age 18-20 years) drinkers completed the two drinking measures and reported on alcohol problems. The STLFB and QF measures converged in assessing typical daily intake, but the STLFB provided more information about situational variations in alcohol use and better identification of regular versus intermittent binge drinkers. Regular binge drinkers reported more alcohol problems. The STLFB is an easy-to-administer measure of variations in alcohol intake, which can be useful for understanding drinking behavior.