This dissertation explored how a teacher learned to teach with and about unfamiliar (to her) media texts in her high school English classroom. This study also examined my role as the researcher/mentor in the teacher’s learning and development process. Through situated learning theories (Lave & Wenger, 1991) and discourse through identities (Gee, 2001; 2014a) theoretical frameworks, this study explored the ways the teacher accepted, resisted, and enacted her figured worlds and identities as an English teacher. Historically, texts in the English classroom consist of novels, poems, plays, and the occasional nonfiction book or essay, and English teacher education and development often keeps these texts at the center of English teachers’ content knowledge. However, research exploring students’ use of multiliteracies in out-of-classroom contexts advocates for a multiliteracies perspective within classrooms. Still, there is a lack of professional development opportunities for teachers to support multiliteracies practices in their classrooms. Further, teachers’ professional development is often provided in stand-alone experiences where teachers learn outside of their classroom teaching contexts. Taking place over a six-month time frame, this study is situated as one-on-one professional development mentoring and included researcher and teacher collaboration in multiple contexts including planning, teaching, and reflection. This qualitative case study (Merriam, 1998) sought to address a gap in the literature in how the collaboration of teachers and researchers impacted teacher learning. Using interpretive analysis (Erickson, 1986) and discourse analysis (Gee, 2014a; 2014b) I developed two assertions: (1) The process the teacher underwent from finding resources to teaching and reflection was complex and filled with many phases and challenges, and (2) I, as the researcher/mentor, served as a sounding board and resource for the teacher/learner throughout her process of learning about, teaching with, and reflecting on unfamiliar texts. Findings of this study indicate the teacher’s identities and figured worlds impacted both how she learned about and taught with unfamiliar texts, and how I approached my role as a researcher/mentor in the study. Further, findings also indicate collaborative, practice-based research models (Hinchman & Appleman, 2017) offer opportunities to provide teachers meaningful and impactful professional development experiences situated in classroom contexts.