This investigation examined grade as a source of systematic variation in the African American English (AAE) produced by students in preschool through fifth grades. Participants were 400 typically developing African American boys and girls residing in low- or middle-income homes in an urban-fringe community or midsize central city in the metropolitan Detroit area. Between preschoolers and kindergartners, and between first through fifth graders, there were no significant differences in the amounts of dialect produced during a picture description language elicitation context. However, there was a significant downward shift in dialect production at first grade. Students who evidenced dialect shifting outperformed their nonshifting peers on standardized tests of reading achievement and vocabulary breadth.KEY WORDS: African American English, dialect, bidialectalism, code switching, language