Performance-based approaches to learning and assessment are consistent with goals for standards-based instruction and show promise as a vehicle for teacher change. Performance assessment involves students participating in an extended, worthwhile mathematical task while teachers facilitate and assess their learning. We designed and implemented a project in an elementary mathematics methods course in which preservice teachers developed performance assessment tasks and then administered these tasks in K-8 classrooms. We present our guiding framework for this project, the project design, and the teaching and learning experiences for project leaders and preservice teachers. Recommendations and reflections are included for others intending to implement similar projects.