We examine how adolescents’ domain‑specific confidence shapes subsequent participation in Science, Technology, Engineering, and Mathematics (STEM) study and vocational training, using longitudinal data from a nationally representative cohort of German secondary school students. We show that domain‑specific confidence measures provide markedly different predictions from composite confidence indices: in line with established models from educational psychology, higher confidence in mathematics and Information and Communications Technology (ICT) increase the likelihood of entering STEM pathways, whereas higher confidence in reading decreases it. These opposing patterns are obscured when confidence is aggregated into a single measure. Our findings demonstrate the importance of distinguishing between domains when studying non‑cognitive determinants of STEM choices and suggest that broad confidence‑building interventions may unintentionally reinforce existing gender disparities in STEM participation.