The purpose of the two studies reported in this article was to evaluate the effectiveness of extended vocabulary instruction during storybook reading with kindergarten students within a small-group intervention setting. Extended vocabulary instruction is characterized by explicit teaching that includes both contextual and definitional information, multiple exposures to target words in varied contexts, and experiences that promote deep processing of word meanings. In Study One, we compared extended instruction of target words to incidental exposure. In Study Two, we compared extended instruction to embedded instruction (i.e., providing simple definitions within the context of the story). Our findings indicated that extended instruction resulted in greater word learning than either incidental exposure or embedded instruction. Moreover, students maintained much of their understanding of word meanings six to eight weeks after instruction. Implications are discussed in relation to a tri-level approach to vocabulary instruction and intervention for kindergarten students at risk for language and reading disabilities. (Contains 3 tables and 1 figure.)