The purpose of this study was to evaluate effectiveness of rich and basic instruction to incidental exposure of target words with first-grade students within the context of repeated shared storybook reading. Participants were 224 first-grade students, randomly assigned to a condition by classroom, from three elementary schools that serve large numbers of students at-risk for experiencing reading difficulties. All three conditions received large group instruction of the storybook intervention in three 20-30 minute sessions over the course of one week. Results indicated that rich instruction was superior to both basic and incidental exposure across all taught measures. These results were maintained at delayed post-test three weeks following the conclusion of the intervention. Implications are discussed in relation to a three-step approach to vocabulary instruction. (Contains 1 figure and 13 tables.)