This study describes some of the tensions and challenges that 9 student teachers faced as they attempted to apply theoretical tools or principles for teaching middle and secondary school English to the realities of practice. Several contexts or activity settings both shaped and complicated the appropriation process, including undergraduate experiences with and prior beliefs about English as a school subject, the preservice methods courses, field work prior to student teaching, and the classroom context for student teaching. To describe the socialization the student teachers experienced that mediated their appropriation of the principles of instructional scaffolding, we identified three modes of participation in teaching middle and secondary school English. For some, teaching included both the learning of classroom routines as well as reflective practice, that is, a theory-based consideration of instructional decisions; for some, teaching was a process of procedural display in that they were absorbed primarily in enacting lessons that worked for themselves and for their students, making it difficult for them to consider the principles underlying their instructional decisions; and for some, learning to teach was a matter of mastering routines, that is, adopting, without adaptation, curricular and instructional practices without concern for students’ understandings or for instructional principles espoused by the teacher education program. The data suggest that the alignment of various activity settings supported the appropriation of teaching tools and a reflective stance toward teaching and learning. On the other hand, when activity settings worked at cross-purposes with one another, they created obstacles for the appropriation of theoretical and practical tools emphasized at the university. This study suggests the importance of understanding the kinds of relationships that student teachers develop within each setting and how social settings get negotiated and identities get constructed as a result of personal history.