For children whose everyday speech differs greatly from the School English (SE) they encounter in academic materials and settings, it was hypothesized that greater familiarity with SE would be associated with more successful early reading acquisition. Sentence imitation and reading skills of 217 urban African American students in kindergarten through second grade (ages 5 to 8 years) were assessed. Children in each grade varied widely in the extent to which their imitations of SE sentences included phonological and grammatical forms that are acceptable in African American Vernacular English but not in SE. Higher familiarity with SE (reproducing SE features more often when imitating) was associated with better reading achievement, and these relationships were independent of memory ability.