A recent hypothesis is that a general factor of personality (GFP) occupies the apex of the hierarchy of personality as well as the apex of the personality disorders in the same way in which g , the general factor of mental ability, occupies the apex in the organization of cognitive abilities (Rushton, Bons, & Hur, 2008 ). High scores on the GFP indicate what is meant by someone having a " good " personality; low scores indicate what is meant by a " diffi cult " personality, in other words someone who is hard to get along with. Individuals high on the GFP are altruistic, agreeable, relaxed, conscientious, sociable, and open, with high levels of well -being and self -esteem. Because the GFP defi nes clear positive and negative poles, it provides potential for understanding the socially " advantaged " (those with high levels of emotional intelligence) as well as the socially " challenged " (those more likely to suffer a personality disorder). The GFP can be viewed as a dimension of social effectiveness.The explanation we favor for the GFP is that it arose through evolutionary selection for socially desirable traits that facilitate performance across a wide range of contexts . This follows a proposal by Darwin (1871) that natural selection acted directionally, to endow people with more cooperative and less contentious personalities than their archaic ancestors or nearest living relatives, the chimpanzees. conjectured that individuals high on the GFP left more progeny, since people prefer as mates, fellow workers, and leaders those who are altruistic, conscientious, and emotionally stable. People able to cooperate in groups were also more likely to win competitions and wars. The alternative to the GFP being substantive is that it results from artifacts of scale construction and from evaluative bias such as responding in a socially desirable manner.The main empirical impetus for identifying a GFP comes from the observation that the Big -Five factors typically intercorrelate, despite claims that they areThe Wiley-Blackwell Handbook of Individual Differences, First Edition. Edited by Tomas Chamorro-Premuzic, Sophie von Stumm, and Adrian Furnham.