This study explored the use of sophisticated vocabulary, complex syntax, and decontextualized language (including book information, conceptual information, past/future experiences, and vocabulary information) in teachers' instructional interactions with children during the literacy block in prekindergarten and kindergarten classrooms. The sample included 33 teachers and 421 children. We examined correlations among these language features and their unique contributions to children's vocabulary learning. Teachers who used more sophisticated vocabulary also engaged in more decontextualized talk about vocabulary and past/future experiences. Additionally, teachers' use of complex syntax was uniquely associated with talk about conceptual information. Both complex syntax and conceptual information talk predicted children's vocabulary learning; however, complex syntax emerged as the sole predictor when accounting for this relationship. This finding suggests that decontextualized talk about concepts, characterized by complex language structures, may facilitate vocabulary acquisition.