Teachers must be proficient at using data to evaluate the effects of instructional strategies and interventions, and must be able to make, describe, justify, and validate their data-based instructional decisions to parents, students, and educational colleagues. An important related skill is the ability to accurately read and interpret progress-monitoring graphs. This study examined preservice special education teachers' graph reading and interpretation skills at two points in time. Participants used a think-aloud procedure to interpret a curriculum-based measurement (CBM) progress monitoring graph, and results were compared to those of CBM experts. Overall, preservice teachers tended to say fewer words than graph experts did. Furthermore, their descriptions of CBM graphs were less sequentially coherent, specific, and reflective. Little change was observed at time 2. Implications for improving teacher preparation in this skill area are discussed. is an Associate Professor of Special Education at Minnesota State University Mankato. Her research interests include understanding and improving teachers' use of data to make instructional decisions, and training and supporting special education teachers in evidence-based instructional practices.Stephanie M. Hammerschmidt-Snidarich, Ph.D., is a postdoctoral research associate at the Center for Applied Research and Educational Improvement (CAREI) at the University of Minnesota. She is also a literacy content specialist for Minnesota Reading Corps and Serve Minnesota, working to develop, research, and implement early literacy intervention programming that addresses the needs of students with reading difficulties. Her research interests include the intersection of student behavior, intervention fidelity, and academic outcomes for students with and without disabilities; data-based decision making; curriculumbased measurement in reading; and early literacy interventions, including computer-adaptive interventions.Christine A. Espin, Ph.D., is a Professor in the Department of Education and Child Studies (Special Education/Learning Disabilities) at Leiden University, The Netherlands. Her research interests include teachers' data-based decision making, curriculum-based measurement in reading, writing, and content-area learning for secondary school students with learning disabilities, and reading comprehension interventions for students with reading difficulties.Kathy Seifert, Ph.D., is a Senior Lecturer and Coordinator of the Learning Disabilities licensure program in the Department of Educational Psychology (Special Education) at the University of Minnesota. Her interests include preparing preservice teachers in the use of data-based decision making through Curriculum-based Measurement and in the use of evidence-based practice in determining appropriate Tier I and II research-based interventions for student with academic, behavioral, and functional disabilities.Kristen L. McMaster, Ph.D., is a Professor of Special Education in the Department of Educational Psychology, University ...