In this quasiexperimental study, the authors investigated the effects of university within school partnership model, within which faculty members acted as teacher-researchers to improve fractional knowledge among middle school (Grades 5-8) students. Students in nine Grade 6 mathematics classes from two public middle schools in Turkey were assigned to two conditions: University within school model instruction and traditional instruction. Pre- and posttest data showed that the students exposed to instruction through the university within school partnership model significantly outperformed their traditional instruction peers on the fractions test. Results indicated that students made significant gains in fractional knowledge in the experimental classrooms and in different subgroup populations. It was suggested that a substantial amount of mathematical infusion through partnership could have a positive impact on middle school students' fractional knowledge. The educational implications of the study were also discussed.