In surveys and semi-structured interviews, Graduate Teaching Assistants (GTAs) discussed the role of reading in their first-year composition (FYC) courses infused with 'writing about writing' and 'teaching for transfer' perspectives. Three transformative reading lenses played a pivotal role in instructors' pedagogies -- deconstructing genres, situating texts in discourse communities, and reading like a writer -- that each embody a paramount threshold concept in Writing Studies: writing is a social and rhetorical activity. GTAs' responses indicate that these transformative reading lenses facilitate students' ability to make reading-writing connections. When students engage texts through these lenses, the act of reading becomes a tool for shaping students' current and future writing development.