The National Center for History in the Schools (NCHS) has been publishing history curricular materials for more than 20 years. Widely used in public and private schools, over 80 of these publications are reproducible teaching units which cover a wide variety of specific issues and dramatic episodes in World and U.S. History. All are organized around carefully constructed lesson plans that rely on primary documents of many kinds. Each teaching unit is the fruit of a collaboration between history professors and experienced teachers in the precollegiate schools. They provide learning objectives, historical background essays, and suggested active-learning classroom activities through which students can practice the historian’s craft, discover for themselves how to analyze evidence, establish a valid interpretation, and construct a coherent narrative in which all the relevant factors play a part. Many of the units have been developed with such organizations as the Autry Center for Western Heritage, the Getty Museum, the Huntington Library, the Asia Society, and the Institute on Religion and Civic Values.