A lack of training maturity is often claimed to be the cause of school leavers’ problems in the transition from school to vocational education and training (VET)—especially for those with lower school certificates. This refers to deficits in e.g. reading and mathematics skills or social competences. Constellations of these dimensions have not yet been investigated. In a Latent Profile Analysis based on NEPS Starting Cohort Grade 9, we explored profiles of academic competences and psychological performance characteristics as well as behavioural and personality-related characteristics among school leavers (no certificate, lower secondary certificate, secondary certificate). We identified five profiles describing subgroups with different constellations of advantages and disadvantages in these characteristics: (1) high achievers with relatively high behavioural and personality-related characteristics (VP), (2) high achievers with relatively low VP, (3) average achievers with relatively high VP, (4) low achievers with relatively high VP and (5) low achievers with relatively low VP. The proportion of school leavers without or with lower secondary certificate was significantly higher among low achievers. In regression analyses, we investigated the profiles’ prognostic validity with regard to the likelihood of entering VET after leaving school. We found lower probabilities among the higher achieving youth, which indicated self-selection into upper secondary programmes at vocational schools. Furthermore, we found that school leavers with secondary certificate persistently showed higher probabilities of entering VET than those with lower certificates. Given the heterogeneity of both groups, this gives rise to criticism of institutional and firm-based selection rationales.