Standards drive critical elements of the American educational system--the curricula that schools follow, the textbooks students read, and the tests they take. Similarly, standards establish the levels of performance that students, teachers and schools are expected to meet. To succeed in the 21st century, all students will need to perform to high standards and acquire mastery of rigorous core subject material. All students also will need to gain the cognitive and social skills that enable them to deal with the complex challenges of our age. The Partnership for 21st Century Skills (P21) Framework for 21st Century Readiness emphasizes life and career skills, learning and innovation skills, information, media and technology skills as well as core subjects and 21st century themes. The release of the Common Core State Standards (CCSS) in 2010 has been an important turning point in the standards movement. For the first time, a majority of states have agreed to a common baseline for academic knowledge and college readiness skills. Currently, over 40 states have begun the challenging work of alignment, integration and implementation of CCSS for English language arts (ELA) and mathematics. Districts have also begun intensive curricular redesign work in response to the Common Core State Standards. As education leaders incorporate the CCSS into school systems, P21 urges them to do so in a way that honors the fusion of the 3Rs (core academic content mastery) and 4Cs (critical thinking and problem solving, collaboration, communication and creativity and innovation). This toolkit is designed for state and district leaders who are interested in implementing the Common Core standards in ways that strengthen the 4Cs. This toolkit contains: (1) Alignment Overview: A high-level summary of how the P21 framework and the Common Core State Standards support each other; (2) Common Core/P21 Examples: Lesson starters that illustrate "what it looks like" to align instructional practices with both the common core and P21 skills; (3) Common Core Resources: Compilation of useful links for states and districts working to implement the Common Core State Standards; and (4) Assessment Resources: Compilation of background reading on the issue of assessment and the 4Cs. Appendix includes: P21 Framework Definitions. (Contains 1 footnote and 23 resources.)