The purpose of the study was to examine the efficacy of a 4-week dialogic reading intervention with rural Bangladeshi preschoolers with the intention of increasing their expressive vocabulary. Eighty preschoolers randomly selected from five preschools participated in the 4-week program. Their expressive vocabulary, measured in terms of definitions, was tested on 170 challenging words before and after the program and compared with that of control children who participated in the regular language program. Both groups were read in Bangla eight children’s storybooks with illustrations, but the dialogic reading teacher was given a set of “wh” and definitional questions to enhance children’s verbal participation. The mean vocabulary scores of dialogic program children increased from 26% to 54% whereas the control children remained at the same level. Results are discussed in terms of the successful application of dialogic reading to low-resource preschools.