Although research supports the effectiveness of the multitiered system of supports (MTSS) on academic and behavioral outcomes, districts aim to engage in data-based decision making and examine the effectiveness of their own MTSS implementation. This case study describes how one regional education service agency (RESA) in the Midwest implemented MTSS and the effect of implementation on rates of specific learning disability (SLD) identification and the achievement of students receiving special education services under the category of SLD on the state assessment. Case data suggest MTSS effectiveness varies between schools and districts within a system, subpopulations of students, and type of outcome examined. Recommendations for future MTSS work among practitioners include: (a) professional development/coaching for educators that implement Tier 1 and Tier 3 instruction and intervention, (b) collaboration and coordination between systems and departments, and (c) data reviews that include the integrity of MTSS implementation, personnel changes, and the purpose of each type of data collected.