Assessing Aberrant Personality in Managerial Coaching: Measurement Issues and Prevalence Rates across Employment Sectors FILIP DE FRUYT 1 * , BART WILLE 1 and ADRIAN FURNHAM 2 1 Department of Developmental, Personality and Social Psychology, Ghent University, Belgium 2 Research Department of Clinical, Educational and Health Psychology, University College London, London, UK Abstract: The convergent and discriminant validity of two methods to assess a broad spectrum of aberrant personality tendencies was examined in a large sample of managers who were administered the NEO-PI-R (N = 11 862) and the Hogan Development Survey (N=6774) in the context of a professional development assessment. Five-Factor Model (FFM) aberrant compounds, defined as linear combinations of NEO-PI-R facets, converged for the antisocial, border- line, histrionic, avoidant and obsessive–compulsive tendencies with their respective Hogan Development Survey counter- parts. Alternative linear FFM combinations did improve convergent results for the schizoid and obsessive–compulsive pattern. Risk for various aberrant tendencies was roughly equal across different employment sectors, with a higher prev- alence of borderline, avoidant and dependent tendencies in the legal and more histrionic tendencies in the retail sector. Adopting FFM aberrant compound cut-offs developed for coaching purposes to flag at risk individuals showed that 20% to 25% of all managers qualified for at least one and 10% to 15% were flagged as at risk for two or more aberrant tendencies. The theoretical implications and the repercussions of this research for the design of professional development and coaching trajectories are discussed. Copyright © 2013 John Wiley & Sons, Ltd. Key words: dark side traits; aberrant traits; HDS; FFM personality disorder compounds; coaching; personnel development; management development The past years witnessed an increased attention in the Industrial and Organizational (I/O) psychological literature for dark side personality tendencies, also referred to as subclinical or maladaptive traits or dysfunctional personality tendencies (De Fruyt et al., 2009; Furnham & Taylor, 2004; Judge & LePine, 2007; Moscoso & Salgado, 2004; Rolland & De Fruyt, 2003; Wu & Lebreton, 2011). These dysfunc- tional patterns are assumed to be manifested when individuals get out of their psychological comfort zone in situations of stress or in the absence of external control mechanisms. In this respect, dark side tendencies can be considered as a risk factor for the demonstration of maladaptive functioning at work. Many individuals have often learned, formally or informally, to deal and cope with these sharp sides of their personalities, and such tendencies can hence be considered to be dormant or operating under the radar, rather than be manifest, but these may be activated quickly and abruptly in interaction with situational circumstances. For still other individuals, such tendencies play a more manifest role in their day-to-day functioning. The dark side is contrasted with the ‘bright side’ of personality functioning, reflected in self-descriptions of personality (Hogan, Hogan, & Kaiser, in press 2010). This bright side is typically studied using general trait measures, such as the traits encompassed by the Five-Factor Model (FFM; McCrae & Costa, 1996), whereas dysfunctional per- sonality tendencies are assessed using more specific invento- ries focusing on one (e.g. narcissism) or a set of maladaptive traits. Although dark side traits have been mainly studied from the perspective of the Dark Triad (Paulhus & Williams, 2002), that is, the dysfunctional tendencies of narcissism, antisocial traits and Machiavellianism, research lines corroborating on clinical manifestations of personality dysfunction have ex- panded the scope within I/O psychology to also include sub- clinical manifestations of the 10 personality disorders listed on Axis-II of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 2000), that is, the paranoid, schizoid, schizotypal, antisocial, borderline, histrionic, narcissistic, avoidant, dependent and ob- sessive–compulsive personality tendencies. Robert and Joyce Hogan developed the Hogan Develop- ment Survey (HDS; Hogan & Hogan, 2001), assessing the core of the personality disorders included in the DSM, supplemen- ted with the passive–aggressive personality disorder referred to in the DSM-IV appendix. From a different angle, De Fruyt et al. (2009) and Wille, De Fruyt, and De Clercq (in press) recently argued to conceptualize dysfunctional personality tendencies in the workplace from the perspective of general trait models such as the FFM, adopting a set of FFM com- pound scales proposed by Miller and colleagues (Miller, Bagby, Pilkonis, Reynolds, & Lynam, 2005; Miller, Lynam, Pham-Scottez et al., 2008; Miller, Lynam, Rolland et al., *Correspondence to: Filip De Fruyt, Department of Developmental, Personality and Social Psychology, Ghent University, H. Dunantlaan 2, B-9000 Gent, Belgium. E-mail: Filip.DeFruyt@ugent.be European Journal of Personality, Eur. J. Pers. (2013) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/per.1911 Received 10 October 2012 Revised 6 December 2012, Accepted 6 December 2012 Copyright © 2013 John Wiley & Sons, Ltd.