Modern dream studies began when Sigmund Freud=s book ?The Interpretation of Dreams= was first published more than 100 years ago. For the first time in cultural history, dreams were regarded as individual creations arising from the life of the mind and became a way of exploring the unconscious. From then on, dream interpretation was a core element of psychoanalytically based psychotherapy. Originally based on purely psychological findings, it developed further to become a comprehensive dream science in which psychological and neuroscientific approaches meet. The author traces these developments. He takes different depth-psychological approaches into account and discusses findings from neuroscientific dream research. Finally, he explains the special features of the treatment using low-structured dreams, which occur in individuals with severe personality disorders and in a state of deep regression.