A troubling gap exists between the current state of history assessment and the knowledge and skills deemed essential for students to thrive in the 21st century. We propose a new assessment of historical thinking that represents a promising alignment with extant cognitive research, as well as with the practices that undergird the discipline. In this article, we discuss the design of the Assessment of Historical Analysis and Argumentation (AHAA), as well as the accompanying scoring rubric, and report findings from our administration of multiple forms of the exam with secondary students (N = 618). Evidence indicates that the exam captured student historical thinking about documents and that the items prompted students to construct a cognitive representation of intertextual reasoning. Given the dearth of assessments that capture student historical thinking about documents and their understanding of content, we believe the AHAA has the potential to be an important instructional resource.