Many schools around the country are getting positive responses implementing Response to Intervention (RTI) within a Multi-Tiered System of Support (MTSS) framework (e.g., Abbott, 2011; Ball & Trammell, 2011; Buysee & Peisner-Feinberg, 2009). RTI refers to an instructional model that is based on a student's response to instruction. RTI instruction is often divided into three tiers, namely, Tier 1 (T1) whole class instruction, Tier 2 (T2) small group intervention, and Tier 3 (T3) individualized intervention. RTI emphasizes (1) universal screening to identify children who need additional support; (2) a continuum of best practice interventions that increase in intensity; and (3) ongoing progress monitoring (PM; Abbott et al., 2008). At the classroom level, a team is created and may include the classroom teacher, paraprofessionals, and sometimes special education teachers and administrators. The classroom team works to create an action-oriented plan through data-driven decision making (DDDM), which is a process used to make instructional decisions based on verifiable data. This article describes L3D, which is a preschool literacy program, grounded in DDDM that was developed across two federally-funded research projects (Greenwood, Abbott, Atwater, Beecher, & Petersen, 2012; Sheridan, Carta, Knoche, Abbott, & Clarke, 2011). The first project investigated different components within an MTSS model and created a DDDM tool called the Tune-Up Checklist (TUC; see Appendix A; Abbott, Knoche, Beecher, Peterson, & Payette, 2012). The TUC is a self-reflection tool that guides instructional implementation. The second project expanded the TUC to include fidelity of implementation checklists and created L3D.