The aim of this study was to investigate the differentiation practices of mathematics teachers within the framework proposed by Tomlinson (2016). Tomlinson's framework outlines general principles of differentiation and how teachers tailor these to meet students' diverse needs. Previous research suggests that differentiation among teachers is not utilized to the necessary extent. One primary research question was established to guide this study: How do teachers' application of general differentiation principles relate to the practical operationalization of teaching, considering the unique needs and conditions of their students? A qualitative approach was employed, utilizing semi-structured interviews and observations to gather data and analyze teachers' approaches to differentiation. The study involved the participation of four teachers from three different schools. Through coding, thematization, and summarization a deductive thematic analysis was applied to reveal patterns in teachers' practices. The findings revealed that teachers varied in their differentiation practices across different levels of Tomlinson's framework. Some teachers consistently differentiated across all aspects, while others showed moderate to no differentiation. Furthermore, the study highlighted the importance of addressing and integrating students' needs more comprehensively into differentiation practices. Assessment and routine were also found significant for an effective practice differentiation. The study is of relevance for teachers because it has led to conclusions that can show where the area of improvement in differentiation education lies in the Swedish context. Suggestions for further research include exploring the impact of different teaching materials on differentiation practices, and examining specific areas where teachers differentiate more or less frequently.