The evolution of information systems from their conceptual schemas is an important research area in information systems engineering. In this paper, we aim at contributing to the area by focusing on a particular conceptual modeling construct, the partitions. We analyze the evolution of partitions in conceptual schemas of information systems. We deal with conceptual models with multiple specialization and classification, and consider whether entity types are base or derived. We provide a list of possible schema changes and, for each of them, we give its preconditions, and its effects on the schema, taking into account the state of the information base. In this paper, we deal with conceptual schemas in the UML. However, the results reported here should be applicable to most conceptual modeling languages and also to object-oriented database schemas.