Published online by Cambridge University Press: 24 November 2020
In this chapter, we consider trajectories of change in vernacular African American Language (AAL) based on a set of seven temporal data points, from 48 months of age to post-secondary (19-21 years of age), using a Dialect Density Measure (DDM). Although different trajectories are uncovered, the predominant pattern is the “roller-coaster effect,” in which children’s vernacular index entering school recedes over the first four grades, accelerates during sixth to eighth grade, then recedes again as they proceed through secondary and post-secondary school. Comparison of token-based and type-based inventories show a high correlation in the results, and most individual variables also follow this pattern. However, some variables that are acquired during the later acquisition phase, such as ‘habitual be’ and copula/auxiliary absence, may show divergent patterns over the early lifespan.