This is the first national Australian longitudinal study investigating the economic, personal and social costs of youth homelessness over time across a broad range of locations. Too many young Australians are without any form of safe and secure accommodation. It is estimated that approximately 44,000 Australians under the age of 25 are homeless, but the actual number is likely to be higher. Homeless young people comprise some 42 per cent of the Australian homeless population. Participants have been tracked by researchers over a three year period to see what kind of issues young homeless people face: changes in their circumstances, health and quality of life; how many used services; the types of services they accessed; and whether or not they transitioned from homelessness to permanent accommodation.