The 21st century will require knowledge and skill well beyond the basic levels of reading and arithmetic that American schools know how to produce more or less reliably. Delivering a "thinking curriculum" to all American students requires major reform in the ways schools and districts organize their work. The transformation of the institution of schooling that will be needed to make this aspirational goal a real achievement is daunting. This article examines cognitive science, systems engineering, and social science concepts that are pointing toward a new foundation for policies and practices that may radically improve the proportion of students who can achieve true 21st-century skills. (Contains 11 figures and 1 note.)