P21 Leadership States design new standards, assessments, and professional development programs that ensure 21st century readiness for every student. To become a P21 Leadership State, a state demonstrates commitment from the governor and chief state school officer, and submits an application to P21 that describes the state’s plan to fuse the three Rs and four Cs (critical thinking and problem solving, communication, collaboration, and creativity and innovation) within standards, assessments and professional development programs.