Early detection of child mental health problems in schools is critical for implementing strategies for prevention and intervention. The development of an effective measure of mental health and well-being for this context must be both empirically sound and practically feasible. This study reports the initial validation of a brief self-report measure for child mental health suitable for use with children as young as 8 years old ("Me & My School" [M&MS]). After factor analysis, and studies of measurement invariance, 2 subscales emerged: emotional difficulties and behavioral difficulties. These 2 subscales were highly correlated with corresponding constructs of the Strengths and Difficulties Questionnaire (SDQ) and showed correlations with attainment, deprivation, and educational needs similar to ones obtained between these demographic measures and the SDQ. Results suggest that this school-based self-report measure is psychometrically sound, and has the potential of contributing to school mental health surveys, evaluation of interventions, and recognition of mental health problems within schools. (Contains 5 tables and 1 note.)