Objectives The purpose of this study is to explore the longitudinal relationship between academic helplessness, depression, and smartphone dependence among adolescents.
 Methods For this purpose, data from 2018 (1st) to 2020 (3rd) of 2,590 first-year middle school panel of the Korean Children and Youth Panel Survey 2018 were analyzed with an Autoregressive Cross-lagged Modeling.
 Results The analysis results are as follows. First, the regression effects across all time points of all latent variables were significant. Second, the cross-lagged effects appeared in the same direction across all time points, but different results were derived depending on the variables. Specifically, academic helplessness significantly predicted depression at the next time point, but its predictive effect on smartphone dependence was insignificant. Depression significantly predicted academic helplessness at the next time point and also did smartphone dependence significantly. While smartphone dependence significantly predicted depression at the next time point, its predictive effect on academic helplessness was not significant. Based on the evidence above, it was confirmed that not only the relationship between academic helplessness and depression but also the one between depression and smartphone dependence were of mutual causality, and the relationship between academic helplessness and smartphone dependence had a mutual causal one through depression.
 Conclusions In this study, these findings were discussed with their implications.