While research shows that wellbeing among disadvantaged or marginalised young people is often low, few analyses compare wellbeing across different groups of young people recognised by policy as marginalised, and the non-marginalised. This paper examines the extent to which wellbeing varies across five marginalised groups (young people with disability, young carers, materially disadvantaged young people, young people from non-English speaking background, and Indigenous young people) and the non-marginalised. Analysis was conducted on data from a nationally representative sample of 9–14 year old Australians in school years 4, 6 and 8 (N = 5440), designed following extensive consultations with young people. Their perspectives shaped the construction of the wellbeing index, operationalised using 12 indicators within domains of family, peer relationships, health, school, and life satisfaction. Analysis found a significant gap in wellbeing between young people with disability, young carers and materially disadvantaged young people on the one hand, and the non-marginalised on the other. Analysis also found gaps between Indigenous young people and the non-marginalised but these were mostly not significant. However, there was little difference in wellbeing between young people from non-English speaking background and the non-marginalised. For four of the five groups, gaps were larger among 13–14 year olds than among 9–12 year olds. Young people from non-English speaking backgrounds were exceptions in this respect. Latent Class Analysis was used to identify different wellbeing clusters. Odds of three marginalised groups (with disability, carers and materially disadvantaged) being in the lowest wellbeing cluster were particularly high, after controlling for other factors. However, half of those in the lowest wellbeing cluster were not in any of the marginalised groups. The analysis concludes that young people’s wellbeing can best be enhanced through universalist policies that seek to include everyone rather than only through targeting specific groups.