The new literacy studies (NLS) is a tradition of research that includes ethnographic work on literacy that has many applications for classroom teachers. The NLS include explorations of local literacies and critical literacy as well as the notion of literacy itself. When teachers draw on the NLS, students are able to draw on their practices in critical and transformative ways. However, NLS perspectives have not been used to examine how teachers are prepared in pre-service programs and the ways critical literacy practices develop. This paper examines how two pre-service teachers learn to take up definitions of local literacies in their work with students from racially, linguistically, and culturally diverse backgrounds in practicum settings. They use approximations in literacy teaching to design practices with students, demonstrating the process of becoming a teacher of literacy. I conclude with recommendations for teacher educators who are interested in supporting such approximations. (Contains 1 table and 7 notes.)