Deliberate self-harm (DSH) is a major health concern, especially for high-risk populations such as incarcerated youth. DSH refers to socially unacceptable, deliberate behaviour that causes harm to the body regardless of intent to die. There is limited research concerning prevalence rates as well as risk and protective factors for high-risk, adolescent groups. Participants were recruited from a correctional facility for youth aged 12-18. Male (n = 36) and female (n = 51) incarcerated adolescents (N = 87; mean age = 15.9) completed a survey that measured social-demographic characteristics, current depressed mood, lifetime alcohol and drug use, perceptions of social support (availability and satisfaction), approach-avoidance coping, problem-solving confidence, and DSH. The prevalence rates (81% lifetime, 74% annual, and 51% while incarcerated) for this mainly Aboriginal and Métis population were much higher than previous offender, community, and hospital findings. Youth reported much higher rates of DSH on a checklist than in response to a general question previously used in such research, suggesting that previously reported prevalence rates are likely grossly underestimated. Hypotheses regarding risk and protective factors were only partially supported. Depressed mood and drug use were positively, directly related to annual DSH frequency. Depressed mood proved to be a significant risk factor as well for incarcerated DSH. Overall, protective factors did not predict DSH well for this group of offenders. Only approach coping was inversely related to DSH frequency. Participants in this study reported very low levels of protective factors, which likely affected the outcome of statistical analyses. In general, youth reported high rates of risk factors and low rates of protective factors. Rates of DSH warranting medical attention increased with duration and frequency of such behaviour, as did actually receiving medical attention. Although 74% of offenders indicated that medical attention had been warranted at least once, only 50% actually received medical attention. Offenders were equally likely to receive medical attention whether they had engaged in DSH once or repetitively. It is likely that offenders prefer to keep their behaviour private, which affects how often they seek medical attention, even if they believe it is warranted. Recommendations are advanced for detecting and responding to DSH in incarcerated youth.