Transinstitutional information systems support collaboration beyond the borders of single health care institutions. Information management in health care networks aims at establishing systematic information processing in order to contribute to the network's strategic goals. Health care networks can be characterized by complex and even conflicting goal systems. Our objective is to propose a framework, which describes organizational characteristics of health care networks. The framework is used to deduce effects of network characteristics on information management. Concluding, we present an architectural approach of a management platform for health care networks. The framework as well as the management platform are parts of our MedoCom approach.