Purpose: This was a comparative study of changes across a school year in multilevel language indicators, including African American English (AAE) features, in stories written by third-grade students participating in a writing lab approach to language instruction and intervention. Methods: Original stories written in September, January, and May by 18 African American and 15 European American students (4 with disabilities in each group) were transcribed, coded, and compared on measures of discourse-, sentence-, and word-level written language features, including rates of AAE. Results: Significant and similar increases were found for African American and European American students in story scores, total number of words, number of different words, and proportion of words spelled correctly. Racial group was a significant between-group factor only for AAE and for sentence correctness measures influenced directly by differences in AAE from standard written English. African American students produced significantly higher proportions of words coded as AAE than European American students in Probes 1 and 2 but not in Probe 3. Almost no associations were found between rates of AAE feature codes and independent discourse- and word-level measures. Discussion: Culturally and linguistically diverse third graders (with and without disabilities) participating in a strength-based writing lab approach make changes in probe stories at the discourse, sentence, and word levels that show them all to be acquiring new skills in written expression. The African American students appeared to be adding dialectal shifting proficiency to their repertoires.