Students who fail to develop proficiency in math skills in the primary grades are more likely to experience difficulties in the math curriculum later on. These students may be in need of a more targeted intervention, or Tier 2 supports, in mathematic instruction. Although the instructional principles of an effective math intervention are becoming better understood, the practice of designing and implementing an effective Tier 2 math intervention system challenges many schools. This article documents a case study of one school's experience in designing a Tier 2 math intervention system for 10 third graders to provide a model of effective Tier 2 systems. (Contains 1 note and 2 figures.)