This paper investigates the role of constraints in limiting and enhancing creativity in engineering design. Based on a review of literature relating constraints to creativity, the paper presents a longitudinal participatory study from Coloplast A/S, a major international producer of disposable medical equipment. At Coloplast, constraints played a fundamental role and the observations show the important, dual role of constraints in terms of being a limitation and a prerequisite for creativity. Too few or too many constraints had a negative impact on creativity, whereas the formulation, rationale and ownership of formal constraints played a crucial role in defining their influence on creativity - along with the tacit constraints held by the designers. The designers were found to be highly constraint focused, and four main creative strategies for constraint manipulation were observed: blackboxing, removal, introducing and revising. Constraints introduced late in a project contributed to the generation of new solutions to old problems, and existing solutions were creatively adopted to satisfy new constraints. This paper recommends creative constraint-handling strategies, as well as identifying potential directions for future research on the relationship between creativity and constraints. © 2012 Copyright Taylor and Francis Group, LLC.