Staff development is aimed at changing practice. Change creates conflict. Little work has been done to gain insight into the conflict that teachers experience in the implementation of staff development. This study examines conflict in a staff development project aimed at increasing teachers' knowledge and implementation of problem-based integrated mathematics and science teaching in a context of high-stakes testing. Findings show that teachers experienced intrapersonal conflict due to perceived differences in values, functional conflicts over values, and environmental stress. Findings suggest several strategies that might be used in staff development to reduce intrapersonal conflict. (Contains 3 tables.)