This article explores the question of why competent evaluators award the ratings they do to college students' expository essays. Essays were rewritten to be stronger or weaker in four categories: content, organization, sentence structure, and mechanics. Twelve evaluators first used a 4-point holistic rating scale to judge the essays' quality. Then they rated whether each of the four rewriting categories in each rewritten essay was strong or weak (perceptions). Analyses of variance revealed

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... nt and organization to affect ratings most (p < .001). Mechanics and sentence structure had smaller effects, which differed when measured by the actual rewriting versus by the perceptions. Mechanics and sentence structure were significant in their interaction with organization (p < .001 andp < .01, respectively).