This article explores articles from the "Journal of World History", from 1990 to 2008, to uncover conceptual devices world historians use in their work. The goal is to identify promising devices for improving world history instruction. While teaching world history is viewed as increasingly important, lack of clarity regarding course structures and teacher preparation has left many teachers wondering how to help students make sense of the subject. This article aims to provide greater coherence in world history by pursuing a line of inquiry parallel to one researchers have used for history education in general: investigating how experts conduct their work to inform educational models. Results show that these world historians argue for and use multiple, nested units of analysis and shifting temporal and spatial schemes. I discuss the instructional implications of these devices and conclude with recommendations for empirical research on teacher and student cognition in world history. (Contains 6 footnotes and 2 tables.)