Background: The Me and My School Questionnaire (M&MS) is a self-report measure for children aged eight years and above that measures emotional difficulties and behavioural difficulties, and has been previously validated in a community sample. The present study aimed to assess its clinical sensitivity to justify its utility as a screening tool in schools. Methods: Data were collected from service-users (n = 91, 8-15 years) and accompanying parent/carer in outpatient mental health services in England. A matched community sample (N = 91) were used to assess the measure’s ability to discriminate between low- and high-risk samples. Results: Receiver operating curves (area under the curve, emotional difficulties = .79; behavioural difficulties = .78), mean comparisons (effect size, emotional difficulties d = 1.17, behavioural difficulties = 1.12) and proportions above clinical thresholds indicate that the measure satisfactorily discriminates between the samples. The scales have good internal reliability (emotional difficulties alpha = .84; behavioural difficulties alpha = .82) and cross-informant agreement with parent-reported symptoms is comparable to existing measures (r = .30). Conclusion: The findings of this study indicate that the M&MS sufficiently discriminates between high-risk (clinic) and low-risk (community) samples, has good internal reliability, compares favourably with existing self-report measures of mental health and has comparable levels of agreement between parent-report and self-report to other measures. Alongside existing validation of the M&MS, these findings justify the measures use as a self-report screening tool for mental health problems in community settings for children aged as young as 8 years.