State and national social studies standards have laid out what young people need to know about history, government, and other social studies subjects, but they do not provide information on what young people actually know and believe about a subject. The perspectives or frameworks of knowledge and beliefs that young people bring to their social studies lessons are significant not only because they can serve as a scaffold or springboard for learning, but also because they serve as filters through which teaching, subject matter, and learning must pass. Young people's perspectives about the social world, like those of historians and teachers, are shaped by their identities as members of families, communities, regions, and nations, as well as by their affiliations with racial, ethnic, religious, and other groups. These identities and affiliations influence if, how, and how much young people engage with social studies teachers and texts in schools and how much they learn from school subjects. This article summarizes research that has examined the relationships among children's, adolescents' and adults' social identities (their national, racial, ethnic, and gender identities) and their knowledge of, engagement with, and beliefs about texts and tasks related to the study of national history. The purpose is to bring to teachers' awareness the multiple forces that shape and differentiate young people's understanding of national history. With this awareness, teachers can recognize and build on their students' perspectives and in this way help more students learn.