The purpose of this study is to investigate socio-structural predictors of active school transport (AST) change and to explore the stability and changes of transport modes during school transitions and into early adulthood in Germany. School transport mode, urbanicity level, socioeconomic status, and migration background were assessed in 624 children (8.9 ± 1.1 years, 51% female) and 444 adolescents (14.9 ± 1.7 years, 48% female) which were followed up longitudinally six years later. The results of multinomial logistic regressions and transition probability calculations indicated that residing outside of rural areas at baseline and follow-up predicts retaining or switching to AST in adolescence. Similarly, higher socioeconomic status at baseline predicted retaining or switching to AST in early adulthood. This research suggests that transition periods are crucial understanding AST behavior and may provide new opportunities for tailored AST promotion programs for different age groups.