A rich body of research on streaming or tracking conducted mainly in the USA and UK suggests that teachers have lower expectations of students in lower education streams and adapt their curriculum and pedagogy in line with such expectations. Recent large-scale quantitative research conducted in Flanders (Belgium) shows that teachers teaching in lower status technical/vocational streams share a lower "study culture" and perceive their students as less teachable than teachers teaching higher status general education students, which in turn influences students' educational outcomes. This research builds on these studies by using data from qualitative interviews with secondary school teachers in two Flemish secondary schools to explore teachers' perceptions of students in different streams and their adaptations in terms of curriculum and pedagogy. In addition, the relationship between students' educational achievement and stream allocation is analysed using survey data collected in these two Flemish schools. The results further support the findings of research in this area but also suggest that stratification occurs within streams. Furthermore, students from different streams are perceived to value different forms of cultural and social capital, suggesting the prevalence of social class cultures in different streams. The conclusions discuss implications for further research on streaming or tracking in (Flemish) secondary schools. (Contains 2 tables and 5 notes.)