Childhood insomnias (CI) are a diverse group of sleep-related problems that present across the first 2 decades of life, ranging widely in severity. Little is understood about the origins of Cl which are likely heterogeneous. Nevertheless, effective treatments for younger children have been shown to be efficacious. Defined within a development framework, this article reviews common correlates and causes of Cl during the first two decades. A practical approach to the evaluation and treatment of insomnias among children and youth is presented.