Increasingly, prekindergarten programs with literacy outcome goals are seeking to implement evidence-based practices to improve results. Such efforts require instructional intervention strategies to engage children as well as strategies to support teacher implementation. Reported is the iterative development of Literacy 3D, an enhanced support system for Tier 1 literacy instruction that combines evidence-based strategies for teacher implementation with instructional intervention strategies. A waitlist randomized control trial (W-RCT) design was used over two years. In Year 1, classroom clusters were randomized to two groups, one Literacy 3D and the other a waitlist BAU comparison. In Year 2, the waitlist group received Literacy 3D. First year results indicated that Literacy 3D was promising with regard to improving teachers' use of Literacy 3D practices as well as some intermediate teacher outcomes. Improvements were made and re-tested with the waitlist group in Year 2. Results produced better outcomes in teacher, child, and early literacy outcomes. Implications are discussed. (author abstract)