Teacher education programs and school reform efforts are two mechanisms by which research-based reform messages reach thousands of teachers. Prior research has noted, however, that these messages are often in conflict with longstanding beliefs and norms at school sites. This paper examines teacher agency in the context of school of structure and culture to investigate how both new and experienced teachers grapple with these conflicting messages. Qualitative data reveal that, although the structural and cultural aspects of new teachers' experiences differed in some ways from those of their more experienced counterparts, the approaches they took in addressing change varied within rather than between the two populations. Some teachers felt they were unable to sustain engagement with instructional reform or were only able to do so within their own classrooms or with a limited group of like-minded teachers. Others challenged the institutionalized practices of their sites, but doing so required navigating the structural and cultural elements of their schools that supported institutionalized practices. Many teachers feared that pushing for wider instructional change among their colleagues would jeopardize cordial relationships, but teachers of all experience levels who did push for change found ways to do so while preserving social cohesion. Findings suggest that it may be useful for both teacher education programs and in-school reform efforts to support their participants in engaging in collegial conversations with their peers in ways that deprivatize practice and push against the status quo while still maintaining social cohesion among the members of the group.