Argumentation, a key epistemic practice in science, engages students in socially constructing knowledge claims using evidence. However, teachers need support in integrating argumentation into classroom instruction. We examined teachers' enactments of an educative science curriculum and their curricular decision making for argumentation. Ten middle school teachers enacted lessons that focused on both the structure of an argument and argumentation as a dialogic process. For each teacher, we analyzed videotapes of two lessons and follow-up interviews. Across the teachers, we observed a wide range in teachers' enactments. In some instances, teachers' instructional practices aligned with the underlying epistemic goals, while in other cases the structural aspects were oversimplified and discourse norms followed more traditional teacher-led patterns. To support classroom instruction to move beyond pseudoargumentation, we found three main influences on teachers' curricular decision making in classes with higher quality argumentation: (1) teachers' understanding of argumentation as an epistemic practice (rather than surface level features); (2) teachers as critically reflective curriculum users; and (3) teachers problematizing their prior teaching experiences. As a field, we need to think critically about how to design teacher education experiences to discourage the relabeling of teaching with reform-oriented terms, such as argumentation, and instead support instructional transformation.