Empirical data on design processes were obtained from a set of protocol studies of nine experienced industrial designers, each asked to perform a modest but realistic design task. The designers’ solution concepts were assessed by a panel of experienced educators for overall quality and for constituent aspects, including creativity. From the data, aspects of creativity in design are identified related to the formulation of the design problem and to the concept of originality. Observations from the studies are then applied to a model from artificial intelligence studies of design as the co-evolutionCo-evolution of problem and solution spaces. The general validity of the model is confirmed. However, we propose adapting the model to reflect our observations, such as the possibility in creative design of structuring the solution space prior to the problem space (e.g. the designer applying prior knowledge of precedents), rather than the other way around. We also propose refinements to the co-evolution model, suggesting relevant new concepts of ‘default’ and ‘surprise’ problem/solution spaces.