As modular production becomes increasingly widespread in globalized manufacturing industries, many components constituting a final product are being developed and produced by collaborating part suppliers who have the ability to design their own parts by themselves without aid from the original equipment manufacturer (OEM). In this collaborative product development, the important aspect to expedite engineering changes is that engineering change information should be represented precisely in a designer-friendly form and shared among participating companies in an effective manner. However, all part suppliers and an OEM typically do not use the same computer-aided design (CAD) system and they are reluctant to share their CAD data with other cooperating companies owing to the policy of protecting corporate intellectual property. These circumstances make it difficult for collaborating companies to conduct engineering changes, since a part supplier who is responsible for one part of a product needs other CAD part model data designed by other companies for the engineering changes in the typical CAD assembly modeling of a product. In this article, a neutral reference model that consists of a neutral skeleton model and an external reference model is proposed as a new medium for the sharing and propagation of engineering change information among collaborating companies.