This national implementation study aimed to evaluate the effectiveness of Tier 2 structured literacy teaching set within a multi-tiered system of support. Case-controlled matching was used to determine the impact of the implementation for 1,265 5-year-old children. One comparison group included 1,265 children who were matched to the experimental group on demographic and reading variables (i.e., a reading-matched control). The second comparison group included 1,265 children who were matched on demographic factors but presented with relatively stronger reading skills (i.e., demographically matched control). Tier 2 participants scored higher in reading and spelling than their reading-matched peers following intervention. Further, their reading and spelling did not differ from the demographically matched control group following intervention. Results suggest that timely and effective Tier 2 teaching support can be delivered at scale. The critical role of professional development and resourcing to facilitate implementation of evidence-based structured literacy teaching practices at a national level is discussed.