Indigenous people are a vulnerable and disadvantaged population whom collectively face much higher levels of health risks and challenges than non-Indigenous people. Indigenous youth in particular represent a population that are at even greater risk, as interaction between socio-economic, geographic, and cultural differences contributes to a lack of opportunity for youth to experience positive outcomes in a school environment. This cumulative disadvantage is problematic as it not only has a negative impact on young person’s social, emotional, and psychological well-being, but serves to potentially undermine initiatives that aim to ‘Close the Gap.’ Unfortunately, one of the difficulties in assessing psychosocial well-being amongst Indigenous young people relates to the fundamentally different concepts of what constitutes ‘mental health’ across Indigenous and non-Indigenous cultures. In response to this, Westerman (2007) developed a set of scales to measure the social and emotional well-being of Indigenous adolescents, the Westerman Aboriginal Symptom Checklist – Youth (WASC-Y). While she has provided preliminary evidence of the reliability and validity of this measure, further independent evaluation is important. The current research involved the large-scale survey of Indigenous young people attending an independent school for Indigenous students (i.e., the Murri School) located in Brisbane, Queensland. Parents, teachers, and youths were requested to complete relevant versions of measures, including: the WASC-Y, SDQ, and ASEBA (viz. the CBCL, TRF and YSF, respectively). Result found internal consistency of the WASC-Y subscales to be acceptable, and cross-scale correlations indicate that all subscales assess relatively independent constructs. Further, the concurrent validity of the WASC-Y was good with the subscales correlating in a theoretically meaningful way with other measures of psychopathology. High levels of mental health problems were reported on the WASC-Y, with all males and 88.9% of females scoring above the clinical cut-off on two or more subscales. Prevalence rates of mental health problems as measured by the SDQ, YSR, and TRF scales were also high, but varied in accordance with the relative agreement between informants across measures. Implications of these results, including a discussion of the methodological difficulties (e.g., obtaining a reliable outcome measure, parental engagement) and recommendations for future research that can address these issues are discussed.