Decades of research find that effective school leadership and access to high-quality early education are two of the most important determinants of educational outcomes. School principals affect both teacher and student performance and play an important role in turning around troubled schools. High-quality education, from prekindergarten (pre-K) through third grade builds foundational knowledge and skills that prepare students for long-term success. Although governors have acted in recent years to address these two issues separately, efforts to harness the potential of school leaders to promote high-quality education for young children have been more limited. Most states' principal preparation systems could be improved to better equip elementary school principals to evaluate pre-K through third-grade (P-3) teachers, support improvements in teaching and learning, and guide teachers in using curricula and assessments in the earliest grades. This issue brief makes the case for why governors should consider building elementary school principals' capacity as P-3 leaders and outlines specific state policy strategies for accomplishing this goal. To illuminate how this works in practice, a case study from Illinois highlights how this state is including early learning content in the principal preparation process.