Teachers' instructional practices are critical for guiding students' engagement in scientific practices within the classroom knowledge building community. In this study, we seek to understand how teachers' instructional supports of epistemic aspects involved in scientific modeling may influence students' meaningful engagement in the practice. In particular, we examine two upper elementary teachers' epistemological messages about modeling over the course of a model-based unit and focus group conversations in consensus model activities to explore the relationship between teachers' instructional supports and students' practice. The results suggest that each teacher was sharing complex messages about various aspects of the modeling practice ranging from procedural to epistemic. Further, those messages were then reflected in students' work. Our findings indicate that teachers' (a) foregrounding of epistemological messages, (b) consistency in emphasizing those messages, and (c) unpacking of those messages may play an important role in how epistemological ideas about modeling are taken up by students. We conclude the paper by discussing implications for supporting teachers in meaningfully enacting modeling practice.