Educators are discouraged from focusing only on the interventions listed in this report. There may be others that were not included because the research supporting them was not publicly available. Others may have been excluded because they were too new to have a strong evidence base. The most recent legislation also opens opportunities to receive funding for implementing new and innovative leadership interventions using Tier IV evidence.

Tier IV evidence is less rigorous than the first three tiers. But state and local decision makers should interpret the definition of Tier IV evidence conservatively. Initiatives should have a theory of action grounded solidly in research and have potential for more-rigorous validation.