BackgroundAlthough school-based programmes for the identification of children and young people (CYP) with mental health difficulties (MHD) have the potential to improve short- and long-term outcomes across a range of mental disorders, the evidence-base on the effectiveness of these programmes is underdeveloped. In this systematic review, we sought to identify and synthesise evidence on the effectiveness and cost-effectiveness of school-based methods to identify students experiencing MHD, as measured by accurate identification, referral rates, and service uptake.MethodElectronic bibliographic databases: MEDLINE, Embase, PsycINFO, ERIC, British Education Index and ASSIA were searched. Comparative studies were included if they assessed the effectiveness or cost-effectiveness of strategies to identify students in formal education aged 3–18 years with MHD, presenting symptoms of mental ill health, or exposed to psychosocial risks that increase the likelihood of developing a MHD.ResultsWe identified 27 studies describing 44 unique identification programmes. Only one study was a randomised controlled trial. Most studies evaluated the utility of universal screening programmes; where comparison of identification rates was made, the comparator test varied across studies. The heterogeneity of studies, the absence of randomised studies and poor outcome reporting make for a weak evidence-base that only generate tentative conclusions about the effectiveness of school-based identification programmes.ConclusionsWell-designed pragmatic trials that include the evaluation of cost-effectiveness and detailed process evaluations are necessary to establish the accuracy of different identification models, as well as their effectiveness in connecting students to appropriate support in real-world settings.