Purpose: This study aimed to examine the effect of an intensive vocabulary intervention embedded in e-books on the vocabulary skills of young Spanish-English speaking English Learners (ELs) from low SES backgrounds. Methods: Children (288) in kindergarten and first grade were randomly assigned to treatment and read-only conditions. All children received e-book readings approximately 3 times a week for 10-20 weeks using the same books. Children in the treatment condition received e-books supplemented with vocabulary instruction that included scaffolding through explanations in Spanish, repetition in English, checks for understanding, and highlighted morphology. Results: There was a main effect of the intervention on expressive labeling (g = 0.38) and vocabulary on the PPVT (g = 0.14) with no significant moderation effect of initial PPVT score. There was no significant difference between conditions on children's expressive definitions. Conclusions: Findings substantiate the effectiveness of computer implemented embedded vocabulary intervention for increasing ELs' vocabulary knowledge. Implications: Computer-assisted vocabulary instruction with scaffolding through Spanish explanations, repetitions, and highlighted morphology is a promising approach to facilitate word learning for ELs in kindergarten and first grade. [This is the online version of an article published in "Journal of Speech, Language, and Hearing Research." For the final published version of this article, see EJ1187764.]