Harvard Graduate School of Education will examine the impact of a vocabulary development intervention, dialogic reading, for Head Start Latino English Language Learners (ELL). In addition, the researchers will assess the effect of including the home language in the intervention process. Study participants will consist of 137 ELL children from ten Head Start classrooms. The intervention will occur over 12 weeks. Children will be assigned to one of three treatment conditions: Spanish-English; English-only; and a comparison group. Children in the two treatment groups will read two books per week and be introduced to six target vocabulary words each week that are found in both books. General vocabulary knowledge in Spanish and in English will be assessed using the Spanish and English versions of the Receptive One-Word Picture Vocabulary Test (ROWPVT and ROWPVT-SP). Target word vocabulary knowledge will be measured in Spanish and English using researcher-developed assessments modeled on the ROWPVT and ROWPVT-SP. Results from this study will contribute to the current knowledge of effective early literacy for Head Start English language learners and provide Head Start teachers with the skills to implement dialogic reading as part of their daily curriculum.