After-school programs offer a superb venue to teach twenty-first century skills. The programs enable students to explore new fields, use new technology, meet real-world challenges, and develop mastery. They create a new civic space in which young people can forge positive relationships with adults, learn the joys of productive work, and be recognized as contributors to their communities. Indeed, after-school programs are emerging as one of the nation's most promising strategies for developing twenty-first century skills. This article examines the current and potential role of after-school programs in building twenty-first century skills--a set of competencies that include creativity, using data to solve complex problems, nuanced oral and written communication, and the ability to work well on diverse teams. The authors present examples, research, and expert testimonials that suggest the power of out-of-school learning to boost twenty-first century skills. (Contains 1 figure and 24 notes.)