Research Findings: A social validity measure was used to examine 56 bilingual preschool teachers' perceptions and acceptability of an interactive shared book reading vocabulary intervention implemented in English with Spanish-speaking preschool children (N = 334) in a dual language program model. Social validity outcomes indicated that bilingual teachers believed the shared book reading vocabulary approach was effective and could be feasibly managed to expand preschool dual language learners' (DLLs) content vocabulary knowledge by building deep knowledge networks around the worlds of science and social studies even as students' English abilities were still developing. Researchers also found a significant positive association between teachers' social validity outcomes and DLLs' English vocabulary outcomes of taught words, warranting further research in this area. Practice or Policy: Teacher perceptions of intervention effectiveness and usability are important and may serve as a barometer for whether teachers may be willing to both adopt and persist with intensive practices when there is a benefit for young children acquiring academic content in a second language. Results suggest, however, that customized and more responsive PD may be especially important to support teachers' ability to facilitate analytical discussions using academic words when DLLs are in the beginning stage of English language production.