The National Archives of Australia, as the archives and records authority for the Government of Australia, has a requirement to ensure that high value digital records created through the business activity of Australian Government agencies are accessible indefinitely. However, indefinite preservation is extremely difficult when dealing with digital records encoded in proprietary data formats.The National Archives of Australia's digital preservation project, which has been underway since late 2000, aims to develop a methodology for preserving digital records so they will remain accessible over time. The National Archives approach is focussed on the centrality of data formats as the key to viable long-term preservation of digital records. To implement the approach the Archives is developing or adopting a range of open data formats in XML which will be used as schema to transform original digital objects into XML data formats, a process we refer to as ‘normalisation’.The first section of the paper provides the context for the NAA digital preservation project. It will discuss the policy approach developed by the National Archives and the performance model adopted. The second half of the paper will describe briefly the preservation process being trialled at the National Archives.