This investigation identified dimensions of narrative, persuasive, and expository writing in Grades 1 to 12 and assessed the contribution of speech-language pathologists' (SLPs) indices to scores on teachers' 6 traits rubric. Findings could facilitate development of effective intervention programs for writing. A corpus of narrative, expository, and persuasive writing samples (N = 418) was analyzed for microstructure and macrostructure. Each genre revealed five dimensions. Writing quality included the 6 traits. "Accuracy" contained errors of spelling, capitalization, and punctuation. "Complexity" encompassed mean length of T-unit and clausal density. "Productivity" included total number of words and number of different words for all genres, plus macrostructure for persuasion. "Genre" included macrostructure measures for narration and exposition and use of compromises for persuasion. Productivity scores predicted 6 traits for narration and persuasion, highlighting the important contribution of vocabulary to writing. Accuracy predicted 6 traits only for narration. Indices of genre-specific macrostructure predicted 6 traits total for all three genres.