Despite the fact that Curriculum-Based Measurement(CBM) slopes have been used to evaluate the effectiveness of interventions in research on learning disabilities, there is a lack of empirical research for supporting the technical adequacy of CBM slope. This study examined the best conditions for calculating CBM slope. In order to examine these conditions, this study contained two independent variables(the amount of residual error and the number of data points) and four dependent variables(reliability, validity, RMSE, and MSE). Results of this study indicate that it is necessary to minimize the magnitudes of residual error and collect a minimum of 12 reading CBM data points. Implications and future directions for research are discussed.