Issue addressed: To examine the prevalence and socio-demographic distribution of adherence to national dietary and physical activity recommendations among Australian secondary school students. Methods: Cross-sectional survey of 12,188 students in Years 8 to 11 (aged 12-17 years). Students? self-reported eating, physical activity and sedentary behaviours were assessed using validated instruments administered via an online questionnaire. Results: Less than one-quarter of students (24%) reported meeting the daily requirement of at least four serves of vegetables, while 41% reported consuming the recommended three or more daily serves of fruit. Just 15% of students reported engaging in at least 60 minutes of moderate-to-vigorous activity every day, and only one in five students met the recommendation of spending no more than two hours per day in small screen recreation. Males were performing better than females in terms of fruit intake and physical activity, but worse in relation to frequency of consumption of sugary drinks and fast food, and time spent using electronic media. The proportion of students meeting fruit and vegetable recommendations declined with advancing year level, while lower socio-economic position (SEP) students were faring less well than those from high SEP neighbourhoods, particularly with regards to healthy eating. Conclusions: There is considerable scope for improving young people?s health behaviours in line with national dietary and physical activity recommendations.