Towards Interoperable Preservation Repositories (TIPR) was a partnership among NYU, Cornell University and the Florida Center for Library Automation, funded by a National Leadership Grant from the Institute of Museum and Library Services. The task of preserving our digital heritage for future generations far exceeds the capacity of any government or institution. Responsibility must be distributed across a number of stewardship organizations running heterogeneous and geographically dispersed digital preservation repositories. For reasons of redundancy, succession planning and software migration, these repositories must be able to exchange copies of archived information packages with each other. Practical repository-to-repository transfer will require a common, standards-based transfer format capable of transporting rich preservation metadata as well as digital objects, and repository systems must be capable of exporting and importing information packages utilizing this format. The TIPR project developed and tested a model for repository-to-repository transfer.