The study of extreme variants of phenomena has always been a challenge for science. While the science of personality has roots in several traditions, historically numerous personality theories and constructs for the assessment and explanation of individual differences have strongly been influenced by the progress made in conceptualizing extreme states of psychological functioning. Yet, division of labour resulted in psychiatry and clinical psychology focusing on deviant or maladaptive and personality psychology specializing on the normal range of individual differences. This special issue of the European Journal of Personality is driven by the idea that linking the study of personality and psychopathology offers insights that neither discipline can achieve on its own. Copyright © 2005 John Wiley & Sons, Ltd.