Changes to federal guidelines for the identification of children with disabilities have supported the use of multi-tiered models of service delivery. This study investigated the impact of measurement methodology as used across numerous tiers in determining special education eligibility. Four studies were completed using a sample of inner-city children (N = 150) who were administered a reading screener twice and a reading measure adapted from the state high-stakes reading test. A sub-sample of children identified as At-Risk were administered a comprehensive reading assessment and compared with a randomly selected control group, who were also administered a comprehensive reading assessment (n = 14). A model was developed to estimate the likelihood of special education eligibility based on both theoretical and empirical measurement parameters. Depending on the measurement assumptions of the multi-tiered model, special education eligibility outcomes varied from a low of 0.2% to as high as 11%, depending on the type of measure used, decision-making criteria used at each tier, and the number of tiers in the model. This study highlights the importance of measurement specification, explicit decision-making criteria, and empirical investigation to fully understand outcomes associated with the implementation of multi-tiered models. Implications for special education eligibility policy and practical implications for implementing comprehensive measurement practice in multi-tiered systems at the school level are discussed. (Contains 8 tables and 1 figure.)