In the German system of dual vocational training, in which companies recruit apprentices, graduates from low-level secondary schools (Hauptschule), and particularly those from immigrant families, are at a significant disadvantage regarding access to such apprenticeships. Previous qualitative studies have already pointed to the role of companies' recruiting criteria for mechanisms of indirect discrimination, e.g., their desire for smooth social interaction within the firm. This article builds on a standardized survey among companies to which low-skilled adolescents successfully or unsuccessfully applied for dual vocational training. The company data are matched with secondary longitudinal survey data on the same girls and boys. Which recruiting criteria put ethnic minorities at a disadvantage and hence indirectly facilitate ethnic discrimination? The theoretical approach considers (knowledge of) the immigration country's official language as both a functional requirement and a tool of hierarchical ethnic boundary making. In addition, concepts of social interaction within firms and respective norms as well as of homophily are subjected to an empirical test. Statistical results show that the below-average recruitment chances of applicants with a migration background are somewhat lower if companies stress a social fit criterion in their selection procedures. Furthermore, contrary to the initial hypothesis, ethnic minority youths are only substantially disadvantaged when applying to firms which consider the ability of verbal expression less crucial. Firms which consider this criterion very important may give applicants from immigrant families the chance to present themselves in a job interview and thus dispel ethnic stereotypes like the one that second-generation immigrant youths display serious language deficiencies.