This study examined the effects of implementation of a three-tiered model of reading instruction in a Title I school. The model utilized the Direct Instruction program, Reading Mastery Plus, across all three tiers, wherein instruction was intensified at Tier 2 and Tier 3. Results indicate that all students, including special education and Title I students, made substantial gains in reading achievement. All students improved more than a half of standard deviation from pre- to posttest on all subtests of DIBELS and the Scholastic Reading Inventory. This study provides preliminary support for altering the intensity of one reading program, Reading Mastery Plus, across all three tiers in place of varying programs across tiers. (Copyright © 2011, National Institute for Direct Instruction (NIFDI). All rights reserved).