The college readiness and standard English proficiency of preservice teachers of color are of increasing concern among those working to foster diversity within the teacher workforce. In this article, the author uses positioning theory to examine standard English proficiency and agency among first-generation Black and Latinx preservice teachers, looking specifically at standard English use and instructor feedback as mechanisms for marginalization and/or agency-building. The author then illustrates how positioning theory offers a practical schematic that instructors can use to guide and refine their practice to position preservice teachers in constructive and humanizing ways.