Highlights of major report findings include: (1) the number of young people under juvenile justice supervision declined over the period 2001-2002 to 2004-2005 by 7 percent nationally; (2) the rate for 10 to 17 year olds under juvenile justice supervision declined from 5.1 per 1,000 to 4.8 per 1,000; (3) almost 65 percent of young people were at least 15 years old when they had their first ever juvenile justice supervision; (4) most people completed one supervision period during a year, with community-based supervision being much more common than detention-based; (5) very short supervision periods were more likely to include episodes of pre-sentence remand; (6) supervision periods of medium or longer lengths were more likely to include episodes of sentenced detention or community-based supervision respectively; and (7) differences were found according to demographics such as age, sex, and Indigenous status in both the length and type of supervision. The Australian Institute of Health and Welfare (AIHW) has worked with the Australasian Juvenile Justice Administrators (AJJA) to develop nationally consistent data on one part of this system, juvenile justice supervision. This report is based on two data collections of the Juvenile Justice National Minimum Data Set (NMDS): young people under juvenile justice supervision and juvenile justice episodes (supervision periods). The data includes both community-based and detention-based supervision and covers the period of 2004-2005. Tables, figures, appendixes A-C, glossary and references