A responsiveness-to-intervention (RTI) approach to diagnosing LD is a leading alternative to current practice. This study conducted a meta-analytic review of research on four existing large-scale RTI models and other models implemented for research. Twenty-four effect sizes and unbiased estimates of effect (UEE) were computed. Results found a larger UEE for studies of existing RTI models than those implemented by university faculty for research, but both were strong. The UEE for student achievement and systemic outcomes both exceeded 1.0, but the UEE for systemic outcomes among field-based RTI models was nearly twice as large as for student outcomes. Further, RTI models implemented for research led to an UEE of 1.14 for student outcomes and 0.47 for systemic outcomes. The mean percentage of nonresponders in the studies was 19.8% (SD = 12.5), and an average of 1.68% (SD = 1.45) of the student population was placed into special education. Implications for practice and future research are included. (Contains 1 table.)