Objective Although perfectionism is a prominent personality disposition, only a few longitudinal studies have investigated how perfectionism develops. Theoretical models and qualitative studies have posited that academic success is a developmental antecedent of perfectionism. Yet, quantitative studies tend to interpret the cross‐sectional relationships as academic success being an outcome of perfectionism. In light of these gaps in the literature, the present study was the first to investigate the longitudinal relationships between perfectionistic strivings, perfectionistic concerns, academic achievement, and academic efficacy by examining academic success as an antecedent of perfectionism. Method The study examined 487 adolescents (aged 12–19 years, 54% female) using a cross‐lagged longitudinal design with three time points spaced 4–5 months apart. Results Results showed that academic achievement predicted relative increases in both perfectionistic strivings and perfectionistic concerns, even when including academic efficacy. In addition, academic efficacy predicted relative increases in perfectionistic strivings. Conclusions This is the first study to show that academic achievement is a common factor in the development of perfectionistic strivings and perfectionistic concerns, whereas academic efficacy plays a role only in the development of perfectionistic strivings. Implications of the findings for the development of perfectionism are discussed.