Most psychiatric disorders have their onset in childhood or adolescence, and if not fully treated have the potential for causing life-long psycho-social and physical sequelae. Effective psychotherapeutic and medication treatments exist, but a significant proportion of children and young people do not make a full recovery. Thus, novel, safe, brain-based alternatives or adjuncts to conventional treatments are needed. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are non-invasive brain stimulation (NIBS) techniques which have shown clinical benefits in adult psychiatric conditions. However, in children and young people their efficacy is not well established. The objective of this study will be to systematically evaluate the evidence on clinical effects of NIBS in children and young people with psychiatric disorders, assessing disorder-specific symptoms, mood and neurocognitive functions.