High drop-out rates from Vocational Education and Training (VET) remain a severe problem in VET systems globally. Despite decades of drop-out research revealing numerous influencing factors, the role of trainees’ vocational competence in their drop-out behavior has been neglected. This study aims to define the structure of vocational competence and analyze its effects on drop-out intention. Using longitudinal data from 458 commercial trainees in Germany, vocational competence is measured at three time points using a validated competence test, subdivided into domain-linked and domain-specific dimensions (Gelman and Greeno, 1989). Four different directions of drop-out intentions are considered, enabling a detailed effect inspection of the prevailing research gap. Additionally, factors identified in previous studies, such as educational level, age, language, and the degree of having chosen one’s desired occupation, are controlled for. We conducted 12 rounds of ordinal logistic regression to test three lagged temporal combinations of the effect relationship between vocational competence and dropout intention over different time spans (T0- > T1, T1- > T2, T0- > T2). We find that lower domain-specific competence increases the intention to drop out from VET without qualification over different time spans. Initial lower domain-specific competence also affects trainees’ intention to change their occupation in the final year of training. Furthermore, higher levels of domain-linked competence at the beginning increase the intention to leave VET to pursue higher qualifications in the midterm of training.