Following a high-quality early care and pre-K experience, the kindergarten-through-third-grade years set the foundation upon which future learning builds; and strengthening this continuum creates opportunities for later success. Key components of a quality experience in K-3 include school readiness and transitions, kindergarten requirements, educator quality, prevention, intervention and assessments, and social and emotional learning and mental health. Education Commission of the States researched the policies and regulations that guide these key components in all 50 states to provide this comprehensive resource and many others. The data in this document show at least 20 states require some form of math knowledge for pre-service teacher candidates. Five additional states only require professional development in math for in-service teachers, with three states having requirements for both teacher candidates and current teachers. Ten states specifically identify science and additional STEM subjects in their policies. Twenty-two states plus Washington, D.C., do not specify requirements in statute, rules or regulations.