Teaching vocabularies to young children is critical as vocabulary is related to long-term language, literacy, and academic skills. The current study used a multiple probe design to examine the effects of enhanced milieu teaching with book reading on the use of word approximations in four 2- to 4-year-old females with language delay. The first author implemented the intervention in families' homes for 3 to 5 days a week over 3 months. Through visual analysis and the calculation of effect sizes, the results showed that there was a functional relation between the intervention and the number and frequency of targeted word approximations. After six to 25 intervention sessions, participants used all five targeted word approximations, and the improvements were maintained up to 15 weeks. In addition, the total frequency of targeted word approximations used after prompts and the proportions of prompts used to elicit the targeted word approximations were measured and analyzed. Parents reported high social validity of the intervention via an anonymous questionnaire. Implications for practice and research of family-centered early intervention are discussed.