Book reading has been demonstrated to promote vocabulary. The current study was conducted to examine the added value of an interactive shared book reading format that emphasizes active as opposed to noninteractive participation by the child. Studies that included a dialogic reading intervention group and a reading-as-usual control group, and that reported vocabulary as an outcome measure were located. After extracting relevant data from 16 eligible studies, a meta-analysis was conducted to attain an overall mean effect size reflecting the success of dialogic reading in increasing children's vocabulary compared to typical shared reading. When focusing on measures of expressive vocabulary in particular (k = 9, n = 322), Cohen's d was 0.59 (SE = 0.08; 95% CI = 0.44, 0.75; p less than 0.001), which is a moderate effect size. However, the effect size reduced substantially when children were older (4 to 5 years old) or when they were at risk for language and literacy impairments. Dialogic reading can change the home literacy activities of families with 2- to 3-year-old children but not those of families with children at greatest risk for school failure. (Contains 3 tables.)