Does adolescent depressed mood portend increased or decreased drinking? Is frequent drinking positively or negatively associated with emotional well-being? Do the dynamic relations between depression and drinking differ by gender? Using block-recursive structural equation models, we explore the reciprocal short-term effects (within time, "t") and the cross-lagged medium-term effects ("t" +1 year) and long-term effects ("t" + 2 years) of depressed mood and monthly drinking occasions. Data come from the high school waves of the Youth Development Study, a randomly selected panel of 1015 ninth graders followed to 12th grade. We found that for both genders, depressed mood consistently "decreased" short-term drinking in each grade measured. However, depression "increased" drinking for both genders in the medium-term but only for girls in the long-term. In the other direction, drinking tended to increase depression in the short-term only among ninth-grade boys and 12th-grade girls. Observed trends and differences in the magnitude of the reciprocal effects vary by gender, with drinking being especially deleterious to emotional well-being for boys early in high school (10th grade) but for girls on the cusp of the post-high school world (12th grade). (Contains 2 figures and 1 table.)