The objectives of this study were to determine whether middle school students' writing self-efficacy beliefs make an independent contribution to the prediction of their writing competence and to explore grade level and gender differences in writing self-beliefs (N = 742). Writing self-efficacy was the only motivation construct to predict writing competence in a model that included writing self-concept, writing apprehension, perceived value of writing, self-efficacy for self-regulation, previous writing achievement, gender, and grade level. Girls were more competent writers than were boys, but there were no gender differences in writing self-efficacy beliefs. However, when students were asked whether they were better writers than their peers, girls expressed that they were better writers than were other boys or girls in their class or in their school to a greater degree than did the boys. These findings suggest that girls and boys may use a different metric when responding to traditional self-efficacy scales. Students in Grade 6 reported higher self-efficacy and found writing more valuable than did their older peers, and students in Grade 7 reported lower writing self-beliefs than did students in Grades 6 or 8. (C) 1999 Academic Press.