The purpose of this study was to examine the ways in which teachers use language to promote vocabulary development (i.e., vocabulary talk moves) during science instruction in early-elementary classrooms. Twenty-four total science lessons were recorded by eight teachers, providing 894.27 min of observational data across three timepoints. Discourse analysis was used to identify specific research-aligned vocabulary talk moves. Findings revealed that the cohort of teachers used considerably more moves for building students' knowledge of word meanings than for building students' awareness of words and word learning or for interesting students in words and word learning. Likewise, the cohort used more authoritative moves (teacher telling) than dialogic moves (inviting student exploration and engagement). This study contributes to the field's understanding of the ways that science instruction supports literacy learning and literacy instruction supports science learning in the early-elementary grades. The findings from this study have implications for teacher professional development and policy.