The invention includes a method of synchronizing objects between first and second object stores. A synchronization manager in accordance with the invention maintains a reference store containing identifying data segments corresponding respectively to a plurality of objects that have previously been synchronized between the first and second object stores. An application program that maintains the first object store has associated interfaces that allow the synchronization manager to compare and manipulate objects. One such interface allows the synchronization manager to submit an identifying data segment associated with a particular object. In response, this interface returns a handle that corresponds to the submitted identifying data segment. Another interface accepts a handle that refers to an identifying data segment, and determines if the object corresponding to the identifying data segment has been changed in the first object store since the last synchronization. If it has, the synchronization manager takes steps to update the second object store. If, on the other hand, the object has changed in the second object store, application program interfaces allow the synchronization manager to update the object in the first object store. Objects are transferred through the synchronization manager in an arbitrary, application-specific format that is not determined or understood by the synchronization manager itself.