From a larger longitudinal study of 610 fourth graders in 17 inner city schools, 40 students were randomly selected from 10 classrooms rated high (i.e., top quartile) or low (i.e., bottom quartile) in quality of writing instruction in grades 3 and 4. The written compositions of these students were scored in three ways: (1) according to a rating scale within a reliable scoring rubric, (2) according to countable surface features such as words correctly sequenced, and (3) according to the frequency of specific phonological, morphosyntactic, and orthographic errors in the children's writing. A multivariate analysis of variance was conducted to examine whether quality of writing instruction in grades 3 and 4 predicted students' writing performance at the end of grade 4. Students who received high quality instruction in fourth grade wrote longer compositions with more correctly spelled words than those who had poor quality writing instruction. There was a tendency for two years of quality instruction to be better than one, and, among students who had poor quality instruction in grade 3, compositions were longer in grade 4 when they received quality instruction in fourth grade. Foundational problems of language formulation, production and representation, however, were ubiquitous across the sample. Although these students were within the average range on standardized reading tests, spelling and writing were not developing at average levels. The study confirms the urgent need for more and better writing instruction for high risk, minority children.