The validation process of a gap-filling diagnostic tool that allows educators to monitor children's mental health status by processing parental observations is presented. This quantitative pilot study, conducted on a Hungarian convenience sample, highlighted that the results obtained with the Mental Health Status Questionnaire - parental version are consistent with the results of parent surveys measuring other aspects of children's psychological quality of life, e.g. subjective well-being, peer support or risk of internet addiction. Analyses along the categories of mentally healthy, vulnerable, and endangered calculated from the questionnaire items also revealed significant differences along the above indicators of psychological quality of life, so the measure may also have a screening function. It also provides an informative categorisation of the risk of so-called internalising problems, which are important in childhood and adolescence but tend to be more hidden. However, parental observations should be treated with caution, especially for children in dysfunctional families, so the questionnaire should be used as part of a sufficiently broad pedagogical methodological toolkit, compared to the results of other methods of collecting pedagogical information and working in close collaboration with mental health professionals.