A study was undertaken to determine whether participation in the Wisconsin Writing Project (WWP) could influence teacher behavior to such an extent that it affected student writing achievement. Subjects were fifth grade students in six classes taught by teachers who had attended WWP summer institutes and six classes taught by teachers who had not attended the institutes but who were rated as highly competent by their administrators. Writing samples were collected from the students and holistically scored by two separate evaluators. The results revealed that the students of WWP-trained teachers did create compositions of better quality than did control group students. (FL)