The theories of practice of four novice bilingual teachers regarding their language choices during sheltered English instruction are presented. The investigation followed participants through their preservice program in an urban public university and their first year of teaching in bilingual classrooms. Findings from this study illustrate how theories of practice regarding the use of the native (Spanish) and second (English) languages during sheltered instruction vary among novices and how they change at different points in their individual journeys to becoming bilingual teachers. The novice bilingual teachers in this study used both languages during their sheltered English instruction in different ways, and these language choices are explored in light of existing research on code-switching and hybrid language practices. Implications of the findings for teacher education programs are discussed.