This article offers a critical review of the literature on 21st century knowledge frameworks, with a particular focus on what this means for teachers and teacher educators. The authors accomplish this by identifying common themes and knowledge domains in 15 reports, books, and articles that describe the kinds of knowledge that researchers state are integral and important for success in the 21st century. The authors argue that seemingly disparate frameworks converge on three types of knowledge, as necessary for the 21st century: foundational, meta, and humanistic. Although 21st century frameworks are thought to advocate new types of knowledge, little has actually changed in the new century with respect to the overall goals of education. Despite this sense of continuity, significant changes related to how technologies change all three types of knowledge need to be conveyed. The article ends with specific conclusions and recommendations for teacher education. (Contains 1 figure and 10 tables.)