One of the core dimensions of historical and social science inquiry is "[d]eveloping questions and planning inquiries" according to the National Council for the Social Studies' College, Career, and Civic Life (C3) Framework. Yet existing education research, instructional resources, and assessment have ignored how students frame problems in history and the social sciences or what it might look like to support students' problem framing. This dissertation takes up this work in several ways, focusing specifically on historical and contemporary causal problems. First, the literature review identifies most historical and contemporary causal problems as "wicked" or "ill-structured" and then highlights how historians and other ill-structured domain experts reason about and represent causation. Second, the dissertation presents analysis of three exploratory case studies. The first case study analyzed how an innovative and experienced AP US history teacher represented the characteristics of historical causation for his students. In the two subsequent studies, the dissertation reports how several students worked to frame an ill-structured historical problem and an ill-structured contemporary problem. Unlike traditional document-based inquiry tasks, the task design prompted students to construct an initial problem space rather than jump to evaluate evidence, write an account, or produce a solution. Drawing on the literature and analysis of these studies, the dissertation proposes a framework for researching, teaching and assessing causal problem framing. The framework comprises three key, interrelated dimensions of causal problem framing: "establishing the scale of the problem space, identifying agents and structures, and establishing the interaction of causes." Finally, the dissertation explores the implications of this research and framework, including suggested design principles for creating problem framing activities and interventions to support students in seeing the ill-structured nature of causal problems and the tradeoffs inherent in ill-structured problem spaces. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]