[영문]This study utilizes discrete-time survival analysis to assess the effect of level of academic achievement (both contemporaneously and prospectively) and changes in academic achievement on initiation of marijuana use among rural adolescents in junior high school. In the sample under consideration, 36% of boys and 23% of girls initiated use of marijuana by the end of ninth grade. Consistent with our hypothesis, poor academic achievement is a salient predictor of initiation of marijuana use among both boys and girls. Both contemporaneous and lagged levels of achievement significantly predict initiation. In addition, change in academic achievement is an important predictor of initiation. That is, students who demonstrate a deterioration of their academic achievement over time are more likely to start using marijuana. Poor academic achievement and deterioration of academic achievement should be considered as risk factors for initiation of marijuana use among rural adolescents. Initiatives targeted at improving academic achievement and/or drug use prevention initiatives designed for poor achieving students may help to prevent initiation of marijuana use