Research outh violence (for example, carrying a weapon or attacking someone with intent to harm) is one of the most important social and public health problems worldwide. 1-3 The costs of youth violence stem from harm caused to victims, as well as policing and criminal justice responses and community perceptions of reduced safety. 3,4 Violence was listed in the top three issues concerning young Australians in 2010. 5 Eight per cent of Victorian students in Years 7 and 9 engaged in violent behaviour in 2002, with higher rates among boys than girls. 6 In addition, rates of youth violence are higher in disadvantaged communities 7 and in regional communities with unstable populations and economic structures as well as high unemployment, 8 and lower among youths from immigrant families. 9 There have been reports of increases in violent offences perpetrated by youth in Australia 10 and media reports suggest more youth are violent. 11,12 National population-based surveys could measure whether rates of selfreported violence among youth have changed over time, but Australia does not have such surveys. In this article, we analyse data from Victorian surveys of secondary school students in 1999 and 2009 to examine whether rates of carrying a weapon and attacking someone with intent to harm have increased, after adjusting for sample demographic characteristics.