The Alcohol and Other Drug Treatment Services National Minimum Data Set (AODTS-NMDS) data specifications and collection manual has been prepared as a reference for those involved in collecting and supplying the data for the AODTS-NMDS. It should be particularly useful to staff in Australian Government, state and territory departments, and alcohol and other drug treatment agency staff directly involved in the collection and reporting of the data set. Treatment agency staff looking for information to assist them in providing AODTS-NMDS data to third parties will find details about each data item, such as 'principal drug of concern', in Chapter 4.