Design science research (DSR) aims to deliver innovative solutions for real-world problems. DSR produces Information Systems (IS) artifacts and design knowledge describing means-end relationships between problem and solution spaces. A key success factor of any DSR research endeavor is an appropriate understanding and description of the underlying problem space. However, existing DSR literature lacks a solid conceptualization of the problem space in DSR. This paper addresses this gap and suggests a conceptualization of the problem space in DSR that builds on the four key concepts of stakeholders, needs, goals, and requirements. We showcase the application of our conceptualization in two published DSR projects. Our work contributes methodologically to the field of DSR as it helps DSR scholars to explore and describe the problem space in terms of a set of key concepts and their relationships.