With congeneric mergers, which involve firms with interrelated but not identical business lines that develop diverse products and services, a major challenge for organizations is the development of a common platform that fulfills similar business functions across multiple divisions. Through a field study of a postmerger common platform development initiative, we develop a framework that highlights how environmental and organizational contexts shape the process of common platform development (CPD). Our study provides an account of how the focal organization transitioned to a platform-based approach by achieving a balance between stable and flexible aspects of the common platform through negotiations among the divisions acquired through mergers and acquisitions. These negotiations were enabled through various boundary-spanning activities and the guided successive enrichment of boundary objects used in CPD process.