This study examines the effectiveness of scaling up a vocabulary intervention, pre-K-first grade, using a structured adaptation of the World of Words that allowed teachers some autonomy over its implementation. The purpose was to determine whether such an adaptation could maintain fidelity and promote positive child outcomes. Classrooms (pre-K through grade 1) from 12 elementary schools in a large metropolitan area were randomly selected into treatment (N = 39) and control groups (N = 34). The 21-week intervention involved a shared book reading about science topics, using cross-cutting concepts and vocabulary within taxonomic categories to build knowledge networks. Pre- and posttests examined child outcomes in vocabulary, concepts, and expressive language. Results indicated that fidelity was largely maintained, with significant standardized gains in language and vocabulary for pre-K children. Conversational turns predicted statistically significant improvements in language, suggesting that such adaptations may hold promise for scaling up an intervention.