Qualitative research is the collection and analysis of non-standardised data. This means that qualitative approaches involve a research process with ambiguous research material. The volume takes up these two aspects of qualitative research from the perspective of educational science. On the one hand, it addresses the path of the research process itself, the processual change of perspectives and views and thus the transformative capacity of the research object. On the other hand, it focuses on the handling of diverse material and the potential heterogeneity of the material. The guiding question is: To what extent can qualitative research lead to certainty?