The Business Model Canvas opened the way for the development of a new tool type which we call visual inquiry tools. Such tools build on design thinking techniques to allow management practitioners to jointly inquire into specific strategic management problems. As the interest in and the emergence of visual inquiry tools gains momentum, it is important to formalize the design knowledge that future designers can build on for developing such tools. Thus, we propose a design theory for visual inquiry tools based on the design knowledge accumulated within and across three projects: the Business Model Canvas, the Value Proposition Canvas, and the Team Alignment Map. We outline the design principles (among others) that should be followed for developing visual inquiry tools for other strategic management problems. Our study addresses the lack of guidance in the development of visual inquiry tools and the lack of methodological guidance in design science research on how to theorize and formalize knowledge across multiple projects. We provide a methodological process for analyzing multiple-project data by bridging methodological insights from design science research and qualitative methods from the social sciences.