The same logic that suggests an effect of job attitudes on organizational citizenship behavior (OCB) would also argue for an effect due to personality. It is also plausible that personality could explain the correlation between job attitudes and OCB. A review of the research on personality measures and OCB does not support the case for dispositional affectivity as an important determinant of OCB. A stronger case emerges for the role of some variant of Conscientiousness, although results indicate that the best predictor of OCB is not a ‘factorially pure” dimension of the Big Five, but a constellation or profile of personality facets drawn from different factors of the Big Five.