The Aged Care Assessment Program is an important part of Australia's aged and community care system. It aims to assess the needs of frail older people and facilitate access to care services appropriate to their needs. This data dictionary supports the collection and reporting of the Aged Care Assessment Program Minimum Data Set, by providing definitions for all the data elements in that collection. Use of this Dictionary will help ensure that the data on which the Aged Care Assessment Program is based are uniform and of high quality.