AThe circular economy, it is hoped, is one possible way to radically improveenvironmental sustainability. One suggested path towards a more environmentallysustainable industry that is part of the circular economy concept is for firms to movefrom product offerings to product-service offerings. Such offerings requiresubstantially different business models, such that business model innovation isneeded. In such situations of innovation and change, core capabilities can becomecore rigidities in incumbent firms.Lean startup methodologies are claimed to rapidly and cost effectively developvalidated business models for startup companies. This set of methods is designed forstartup companies but may be useful also for incumbent firms. A collaborative andinterventionist research project together with a company with a long business historytested whether one of these methods, Customer Development, could be of use, thechallenges of using it, and if and how these challenges could be addressed. At thisfirm, it was found that the Customer Development process can be very useful andpotentially work as intended, but requires a conscious setup of the project team. Itseems reasonable to expect that core competencies for the business model in currentuse would become core rigidities that would have jeopardized both the CustomerDevelopment process and its business model outcome without external help to reflectupon important but organizationally embedded presumptions