In most countries, the systems of educational classification are based on administrative criteria. For analyses of the labour-market position of educational categories, however, a classification that demarcates an individual's competencies obtained by the courses attended is a better alternative. In the present paper, we will analyse the substitution processes in the labour market in order to develop an educational classification that is based on the observed possibilities of workers with different educational backgrounds to enter similar occupations. As an additional criterion, we use the recognizability of the groups distinguished. In addition, we incorporate the criterion of statistical reliability. This results in an educational classification with 113 distinct categories.