The aim of this study was to examine whether over the school year boys and girls equally share in performing the behaviors required of hands-on activities (e.g., manipulating the equipment, directing the activity, observing) in the performance-based science classroom. In addition, we examined whether these performance behaviors accounted for changes in boys’ and girls’ science attitudes (i.e., ability perceptions and task value beliefs) at the end of the school year. The sample included 165 students (53% female, mean age = 12.21) in six Grade 5-Grade 8 performance-based science classrooms where the teachers associated with these classrooms were identified not only as exemplary hands-on science instructors but also instructors sensitive to increasing girls’ participation in science. Our results indicated that being actively involved in the performance-based science classroom predicted students’ end-of-the year science attitudes. However, boys and girls did not participate equally in these classrooms. Moreover, we found that for girls, but not boys, there was a decrease in science ability perceptions over the school year, suggesting that boys and girls experienced these classrooms differently.