The census found that the number of homeless students had decreased since 2001. There were 9,389 homeless students in 2006 compared with 12,227 in 2001. Three groups of students were overrepresented in the homeless population: Indigenous (native) students, youth from single-parent and blended families, and teens who had been under government care and protection. An increase in early intervention services apparently accounts for most of the decrease in youth homelessness. There are three categories of "homelessness" widely used in Australia, which consists of "primary," "secondary," and "tertiary" homelessness. "Primary" homelessness occurs when people are without conventional accommodation, such as living on the streets or using cars or railway carriages for temporary shelter. "Secondary" homelessness occurs when individuals move frequently from one form of temporary shelter to another, including boarding houses, emergency accommodation, and short-term stays with other households. "Tertiary" homelessness occurs when people stay in boarding houses on a medium-term to long-term basis, defined as 13 weeks or longer. The census data on homelessness encompassed students in any of these categories of homelessness in the last 3 months. Each school principal (government and Catholic secondary schools) nominated one person to oversee the data collection in his/her school. After extensive followup, 99 percent of the schools completed a census return (2,017 schools out of 2,025). Schools also provided 560 case histories of homeless students. 12 tables and 18 references