The current study investigates the relationships among ethnicity and culture and offending in an incarcerated sample of 242 young offenders in New South Wales, Australia. Findings indicated greater similarities between young offenders from Indigenous and English speaking background (ESB) than between these two groups and culturally and linguistically diverse (CALD) young offenders. CALD young offenders made up 15% of the sample and were disproportionably more likely to commit a violent offence. Compared with Indigenous and ESB offenders, CALD offenders reported less social disadvantage and lower levels of substance abuse. Compared with CALD offenders, ESB and Indigenous offenders were more likely to commit a crime either under the influence of, or to obtain drugs or alcohol. Indigenous offenders began offending earlier than the other two groups and committed a larger number of offences. CALD offenders were more likely to commit the more serious offences of aggravated sexual assault and homicide than ESB or Indigenous young offenders. Compared with both ESB and CALD groups, Indigenous offenders reported more troubled family backgrounds and higher levels of conduct disorder. A number of factors amenable to policy interventions contribute to such observations, such as differential levels of substance use and social disadvantage, and issues leading to overrepresentation of particular cultural groups in the juvenile justice system. The similarities between ESB and Indigenous young offenders on most of the factors assessed in this study, based on commonalities in the kind and relative degree of social disadvantage experienced by these two groups, warrants closer attention.