Major psychiatric disorders such as schizophrenia, bipolar disorder, depression, autism and attention deficit hyperactivity disorder (ADHD) are amongst the most disabling and costly diseases in the world. There is a substantial co-morbidity and familial co-aggregation between the disorders and shared genetic and environmental risk factors. The causes of the disorders are largely unknown and the treatments are ineffective and burdened by adverse effects. Recent genome wide association (GWA) studies have identified a small number of common genetic susceptibility variants, an international effort in which the present consortium is participating. NGS has proven powerful for identifying genes underlying rare monogenic disorders, highlighting the potential of extending the strategy to common complex disorders through larger sample sizes, studies of families and isolated populations, and appropriate weighting of variants by e.g. predicted functional impact and evolutionary conservation, already evidenced by NGS based breakthroughs in complex disorders, including mental retardation, autism and schizophrenia.