Assessing a student's level and rate of improvement on an academic skill is a contemporary approach to the identification of specific learning disabilities. This approach, broadly categorized as responsiveness to intervention, however, does not obviate educators from scrutinizing the psychometric qualities of the data used to make important decisions about students. By way of illustration, we demonstrate that the measurement interval used to calculate rate of improvement can have substantial implications for evaluating the extent to which a student's rate of improvement is judged to be acceptable. Consequently, it is important for educators to fully appraise the method by which a student's rate of improvement is quantified. Suggestions for practical use are offered. Further, we pose a few questions that must be empirically tested if this contemporary approach to the identification of specific learning disabilities is to avoid the limitations of its predecessor ability--achievement discrepancy model.