This study was part of a larger three-year investigation of the effectiveness of a small-group, content-focused (science, social studies) preschool shared book reading vocabulary intervention implemented with Spanish-speaking emergent bilinguals enrolled in a one-way dual-language bilingual program. A subset of bilingual preschool teachers (N = 23), representing treatment teachers from each of the three intervention years, was observed to understand the sustainability of the curricular approach and materials one, two, and three years post-intervention when instructional guidance was no longer provided by the research team. Findings from post-intervention observations and teacher self-reports suggest that teachers continued to implement the intervention approach and materials on some level but the explicit rich vocabulary instruction during the book reading experience was observed less the further teachers were out of the intervention. Implications for research are discussed.