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Relationships have been repeatedly identified as an important object-oriented modeling con- struct for advanced applications Today most emerging modeling standards such as the ODMG object model and UML hence have some support for relationships Similarly, current OODB systems are begining to support structural definition of relationships as well as object level man- agement However, no work has been done on schema evolution of an object model that has relationships In this paper, we present the evolution taxonomy required for evolving relation- ships We also examine the effect of relationships on the pre-existing taxonomy of evolution primitives that is supported by current commercial OODB systems We provide a comprehen- sive contract-based solution within the SERF framework to handle the problem externally, i e , in a layer outside the OODB system Also as part of our work, we extend SERF to now allow for flexible evolution of relationships with user-defined semantics Lastly, we show that SERF is powerful in that it can provide extended schema evolution support in an OODB after its object model has been extended In some cases, such as in aggregate relationships we can use SERF to provide the basic evolution support for the object model extension