The question of how to handle heterogeneity in schools has been broadly discussed in German-speaking regions for years. Due to children's diverse cognitive development, which results from parents' and children's altered living situations and the migration of families, the pupil body is more varied and complex than ever before. At the same time the teaching staff is challenged to pay attention to every individual in their class and to consider every student's individual needs and skills. The heterogeneity debate in school pedagogics often focuses on theoretical backgrounds, political measures, and required as well as already implemented reforms.Apart from a theoretical examination of heterogeneity, the aim of this study is to determine the real circumstances of heterogeneity in primary schools. Special attention is paid to the inquiry of how heterogeneity manifests itself in everyday school life in key stage I, and how it is (re-)produced.For this purpose participatory observations were carried out in one selected first year-, and one second year primary school class. The results were evaluated with qualitative content analysis according to Mayring. In addition guided interviews with form teachers were conducted.The results of this research study show that the claims and reality of heterogeneity differ considerably. The (re-)production of heterogeneity in school for the most part takes place without being questioned. At the same time resources, which would enable handling heterogeneity more deliberately, are lacking. Apart from a well-grounded education, smaller classes and additional teaching staff would be beneficial for handling heterogeneity effectively.