This study examined reading tutors' interpretation of reading progress-monitoring graphs. A think-aloud procedure was used to evaluate tutors at two points in time, before and after a year of service as an AmeriCorps reading tutor. During their service, the reading tutors received extensive training and ongoing coaching. Descriptive results showed a positive change from the Time 1--think-aloud (pretest) to the Time 2--think aloud (posttest). There were statistically significant changes from Time 1 to Time 2 for the majority of graph interpretation variables measured. Data suggest that the right type of support and training may serve to enable reading tutors to develop the skills to contribute to data-based decision-making within multitiered systems.