Despite the fact that much evidence exists to prove that bipolar disorder effects a large amount of children, during the past century doctors have been very reluctant to diagnose bipolar disorder (BPD) before adulthood. In contemporary times, the bias against diagnosing bipolar disorder in youth has been perpetuated by the lack of agreed upon diagnostic criteria that accurately characterise the condition as it typically exists in childhood. As observed by a number of contributors to this volume, this bias extended to birth cohort studies around the world in that instruments designed to detect mania or bipolar disorder were almost never or rarely applied. In the US, the continued use of unmodified DSM-IV criteria to diagnose prepubertal-onset BPD has only recently been tempered by the knowledge that these criteria were developed based solely on observations in adult studies. While the diagnosis of bipolar disorder in childhood still remains the subject of some controversy, today, thankfully, the controversy has shifted from a debate about whether it can be diagnosed to how it is diagnosed. There is now a general consensus among clinicians and researchers all over the world that bipolar disorder does exist in youth and is associated with significant morbidity and mortality; however, the developmental continuity of prepubertal mania with adult bipolar disorder remains yet undetermined and we know very little and are still in great need to learn more about epidemiology, etiology, phenomenology, and treatment of this condition., This book aims to give the first glimpse of the current state of knowledge about paediatric bipolar disorder from around the world and provides an in-depth view of both the differences and the similarities in diagnosis, comorbidity, clinical and research concepts and treatment approaches of colleagues from different parts of the world as well as serves as a source for the historical development of child and adolescent psychiatry, and for the epidemiology of some frequently seen childhood disorders in various countries.