Psychiatry as a professional and scientific enterprise developed in Norway in the middle of the 19th century. During the last part of this century, four state asylums were erected, followed by several county asylums during the first part of the 20th century. From the 1870 s, institutions for private care were established, usually in the vicinity of the asylums. During the middle of the 19th century, psychiatry in Norway was influenced by "moral treatment", but during the end of the century somatic ideas prevailed. After the Second World War, Norwegian psychiatry was influenced by Dutch and British social psychiatry, followed by American psychoanalytic-oriented psychiatry during the 1960-70s. Since the 1980s, the climate changed, with more emphasis on classification and drug therapy. The new American DSM-III also influenced Norwegian psychiatry, and cognitive-behavioral therapies became more prevalent. Norwegian psychiatric research has during the last few decades been characterized by epidemiological studies, clinical follow-ups and twin research.