An assumption that is fundamental to the scoring of student-constructed responses (e.g., essays) is the ability of raters to focus on the response characteristics of interest rather than on other features. A common example, and the focus of this study, is the ability of raters to score a response based on the content achievement it demonstrates independent of the quality with which it is expressed. Previously scored responses from a large-scale assessment in which trained scorers rated exclusively constructed-response formats were altered to enhance or degrade the quality of the writing, and scores that resulted from the altered responses were compared with the original scores. Statistically significant differences in favor of the better-writing condition were found in all six content areas. However, the effect sizes were very small in mathematics, reading, science, and social studies items. They were relatively large for items in writing and language usage (mechanics). It was concluded from the last two content areas that the manipulation was successful and from the first four that trained scorers are reasonably well able to differentiate writing quality from other achievement constructs in rating student responses.