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 constrainthandling strategies, as well as identifying potential directions for future research on the relationship between creativity and constraints.