This study investigated the relationship between middle school students' scores for a written assignment (N = 162) and a process that involved students in generating criteria and self-assessing with a rubric. Gender, time spent writing, grade level, prior rubric use, and previous achievement in English were also examined. The treatment involved using a model essay to scaffold the process of generating a list of criteria for an effective essay, reviewing a written rubric, and using the rubric to self-assess first drafts. The comparison condition involved generating a list of criteria and reviewing first drafts. Findings include a main effect of treatment, gender, grade level, writing time, and previous achievement on total essay scores, as well as main effects on scores for every criterion on the scoring rubric. The results suggested that reading a model, generating criteria, and using a rubric to self-assess can help middle school students produce more effective writing. (Contains 1 table.)