Calls for reform in science education stress the need for inquiry-based, integrative methods that provide students with opportunities to solve authentic problems. Project INSITE, a four-year professional development effort in Indiana, was designed to help teachers integrate problem-centered science methods in their classrooms. This approach was characterized by use of a meaningful driving question anchored in a real-world context; student-conducted investigations that resulted in the creation of products; collaboration among students, teachers, and the community; and use of technology as a tool for gathering and sharing information. Quantitative and qualitative evaluations of the project suggest that it was generally successful in promoting positive teacher perceptions, fostering learner-centered classroom approaches, and leading to implementation of inquiry-based science in many classrooms.