Despite a growing body of evidence demonstrating the value of Tier 1 and Tier 3 interventions, significantly less is known about Tier 2 level treatments when they are added within the context of a tiered continuum of support. The purpose of this article is to systematically review the existing research base for Tier 2 small group intervention studies conducted within a tiered prevention framework. Results indicated that few studies documented fidelity of Tier 1 implementation prior to the addition of Tier 2 interventions. Methods for identifying students to receive Tier 2 supports varied across investigations, but included teacher nomination, use of student data, and/or screening score results. More than half of the reviewed studies demonstrated use of the Behavior Intervention Program: Check-in/Check-out (BEP/CICO), although social skill instructional groups and academic instructional groups were also employed as Tier 2 interventions. Overall, positive results for reducing problem behavior were reported. In addition, school-based personnel implemented the Tier 2 intervention in nearly half of the investigations. Among studies that reported measures of social validity teacher and student perceptions of the treatments were largely positive. Implications for future research are evaluated using criteria from the Society for Prevention Research (Flay et al., 2005). (Contains 2 tables.)