Many studies have explored adolescent depressive mood and deviant behavior separately, and much of this research is cross-sectional. The purpose of the present study is to investigate the relationship between depressive mood and deviant behavior, developmental changes, and gender differences in adolescents from 7th to 12th grade. Using a longitudinal approach, panel sample data were collected from 3,506 junior and senior high school students with the Taiwan Education Panel Survey (TEPS) in four waves in 2001, 2003, 2005, and 2007. Data analysis was performed using the autoregressive cross-lagged model (ARCL) and the latent growth curve model (LGCM). Results showed the following: (1) Depressive mood and deviant behavior generally occur during ninth grade. Ninth grade is a critical turning point in adolescent development that often leads to depressive mood or deviant behavior. (2) Regarding differences in gender, girls experience a higher magnitude of depressive mood, and boys exhibit a higher magnitude of deviant behavior. (3) The correlation between the initial status of depressive mood and the initial status of deviant behavior was positive. (4) The cross-lagged effect of depressive mood on subsequent deviant behavior is significant, and the cross-lagged effect of deviant behavior on subsequent depressive mood is also significant, with boys and girls following significantly different paths when developing depressive mood and deviant behavior. Further suggestions are also presented based on the study results.