At a time when there is great emphasis on teacher quality and the preparation of excellent teachers, this portrait explores the process of one such aspiring teacher, Katie, in the fall of her full-year student-teaching internship. Her mentoring teacher, Kristen, is a veteran fifth-grade teacher at a small elementary school in New Hampshire who uses the same expertise with Katie as she models for use in her classroom. The portraitist, Bryan Mascio, uses classroom observations, interviews, and document analysis as well as his own background as a master teacher to illuminate the complexities of learning, teaching, and learning to teach--while revealing the parallels between these processes. Because teaching is a complex intellectual skill, those who are learning that skill or learning to improve that skill are at their core learners--even while they are simultaneously the teachers of others. By viewing interns through this dual lens, we can best support them to develop as teachers.