Reflection on classroom management as a basic dimension of good teaching is of crucial importance for the professionalization of teachers. This raises the question of what role reflection-related dispositions (knowledge and willingness to reflect) play for the quality of reflection-related thought processes (selective attention and knowledge-based reasoning) with a focus on classroom management. In the present study, this connection was empirically tested using a sample of 193 student teachers using a mixed-method design. In addition to the standardized assessment of declarative knowledge about classroom management and the willingness to reflect, the students were shown a classroom video, which the students should reflect on with regard to classroom management-specific situations. The written reflections were coded using qualitative content analysis with the aim of assessing students’ selective attention, knowledge-based reasoning, and conceptual knowledge relating to classroom management. The results of this qualitative analysis were then quantified for statistical analysis. Regression analyzes revealed that standardized assessment of declarative knowledge can predict selective attention, while conceptual knowledge about classroom management is a predictor for knowledge-based reasoning of classroom management-specific situations. The willingness to reflect is significantly related to both facets of knowledge, but does not represent a predictor for the reflection-related thought processes. The findings are critically discussed against the background of the relevance of reflection processes.