Computer-based complex information systems are used increasingly more often, for a growing variety of purposes, in both educational and professional contexts. Since the effectiveness of information systems will largely depend on the particular purpose and the particular task context at hand, at least part of our research efforts should be directed at studying specific application areas. This paper reports a study on the use of hypertext information systems during architectural-design problem solving. Theoretical notions on design problem solving, such as distinguishing between a problem-structuring and a problem-solving phase, provide us with expectations about the changing informational needs during the design process. Specific information structures are proposed, incorporating design principles from learning research, to accommodate these informational needs. Results of an empirical study indeed showed interactions between design phase and information structure when separately inspecting the outcomes for problem structuring and problem solving. Educational implications include the use of a combination of hierarchical decomposition and cross-referencing for certain instructional goals, such as teaching complexity and abstraction.