A study examined how research concerning an educational innovation such as service learning can be enhanced by the involvement of practitioners. The context was the Service Learning Impact Study, a multifaceted 3-year study of the impact of the Helper Model of service learning on a target population of 1,400 middle school students for whom service learning was required. The study examined the impact of participating in the Helper Model during early adolescence, identified how impact is related to program characteristics and to the types of service students perform, and developed a preliminary framework and exploratory hypotheses concerning the relationship between reflection and the service learning experience. Data were collected from the following: service learning participants and 400 comparison students, teachers, program leaders, and school administrators, using surveys, interviews, and observations. Work with the Impact Study indicated that empirical studies of such educational programs must find ways to work with practitioners because without the involvement of teachers and students, important knowledge that can inform the research and practice may be overlooked, missed, or misinterpreted, and data may be inaccurate. Three key ways were found to work with the practitioners: establishing a teacher working group, maintaining relationships with schools, and collaborating through data collection. Students were involved through approaching them as the experts, establishing a student advisory group, and serving as a service site. (YLB)