With deeper levels of external process integration and a growing number of electronic business relationships, enterprises are striving to become more interoperable with their business partners. While two-way integration linkages have mostly been realized as point-to-point connections with a handful of business partners, new integration technologies such as Web services and XML give enterprises the opportunity to pursue more cost-efficient and scalable ways of external business process integration. This research develops a model for service-based B2B interoperability that leverages Web service technologies for implementing industry standards. The authors instantiate the conceptual model in a concrete B2B scenario in the automotive industry, where a consortium of automotive manufacturers and suppliers are currently redesigning their inter-organizational engineering change management processes. From the evaluation, the authors suggest that the specification of standards related to pragmatics, semantics and syntax has to be complemented by additional design rules which define how industry standards are mapped to a Web service design. The article concludes with a revised model for service-based interoperability and discusses implications for B2B standardization.