A system and method providing cross-ontology multi-master replication is described. In a first embodiment a method for cross-ontology multi-master replication comprising the steps of: storing a database change comprising a property value, the property value having an exporting site property type as defined in an exporting site ontology for an exporting site; using an ontology map to map the exporting site property type to an importing site property type defined by an importing site ontology for an importing site; transforming the property value to an intermediate property value based on the importing site property type; transforming the intermediate property value to a first round-trip value based on the exporting site property type; and determining whether to export the database change to the importing site based at least in part on a comparison between the property value and the first round-trip value.