© Springer International Publishing AG 2016 Virgil Zeigler-Hill and Todd K. Shackelford Encyclopedia of Personality and Individual Differences 10.1007/978-3-319-28099-8_1071-1 Extraversion Aaron W. Lukaszewski 1 (1)California State University, Fullerton, CA, USA Aaron W. Lukaszewski Email: alukaszewski@fullerton.edu Without Abstract Synonyms Extroversion; Gregariousness; Introversion; Sociability; Social attention; Social boldness; Surgency Definition Extraversion is a higher-order dimension of personality variation encompassing individual differences in sociability, assertiveness, positive emotionality, approach tendencies, and status motivation. Introduction The extraversion continuum is one of several basic higher-order dimensions of personality variation (Wilt and Revelle 2008). In what follows, the main research findings regarding extraversion will be overviewed. Phenotypic Description The extraversion continuum is defined by correlated variation in multiple psychological and behavioral facets (Lucas et al. 2000; Wilt and Revelle 2008). At the high end of the continuum, extraverted behavior is defined by gregariousness, boldness, assertiveness, approach tendencies, positive emotionality, and status motivation. Symmetrically, at the low end of the continuum, introverted behavior is defined by shyness, inconspicuousness, submissiveness, avoidance tendencies, and negative emotionality. These and other selected facets of behavior falling on the extraversion continuum are represented in Table 1.Table 1 Selected behavioral facets of variation encompassed by the extraversion continuum