Extending the Spectrum Idea: Child Personality, Parenting and Psychopathology KARLA G. VAN LEEUWEN * , IVAN MERVIELDE, BARBARA J. DE CLERCQ and FILIP DE FRUYT Department of Developmental, Personality and Social Psychology, Ghent University, Ghent, Belgium Abstract The spectrum hypothesis, postulating that differences between referred and non-referred samples are confined to mean level differences, is elaborated by exploring whether the covariation between child problem behaviour and its predictors—child personality and parenting, rated by mothers—is similar in referred (N ¼ 205) and non-referred (N ¼ 596) children and whether personality by parenting interactions can be generalized across samples. Results showed significant mean level differences for all the variables. Both personality and parenting explained problem behaviour, with some differences in strength of the effects across samples. Parenting by personality interactions mainly predicted externalizing behaviour, with benevolence and conscientiousness as the most prominent moderators. Results confirmed that moderators of problem behaviour operate similarly in the two samples, thus corroborating the spectrum hypothesis. Copyright # 2006 John Wiley & Sons, Ltd. Key words: parenting; child personality; spectrum hypothesis INTRODUCTION In research on psychopathology, researchers are still struggling with the question whether differences between normal and abnormal or clinical samples can be conceived as mainly qualitative or rather quantitative (Cole & Baker, 2004; Widiger & Samuel, 2005). This issue is particularly pertinent for research on personality disorders (Livesley & Jang, 2005; Widiger & Frances, 2002). One of the ways to conceptualize the relationships between ‘normal’ personality variation and psychopathology is referred to as the ‘spectrum association’ hypothesis (Shiner & Caspi, 2003), which postulates that a disorder is not a discrete taxon, but rather represents the extreme endpoints of a continuously-distributed European Journal of Personality Eur. J. Pers. 21: 63–89 (2007) Published online 24 November 2006 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/per.598 *Correspondence to: Karla G. Van Leeuwen, Department of Developmental, Personality and Social Psychology, Ghent University, H. Dunantlaan 2, B—9000 Ghent, Belgium. E-mail: karla.vanleeuwen@UGent.be Contract/grant sponsor: Flemish Community; contract/grant number: bel96/32. Copyright # 2006 John Wiley & Sons, Ltd. Received 24 January 2006 Accepted 10 May 2006