Abstract We evaluated two models of the factor structure underlying the variables of Jackson's ( Personality Research Form Manual, 1984) Personality Research Form (PRF). One model posits the well-known Big Five factors of personality. The second model, in contrast, splits the Conscientiousness factor of the Big Five into an Achievement factor, having to do with ambition and hard work, and a Methodicalness factor, having to do with the need for organization and orderliness. Substantial support for the latter of these two models is presented in three studies, both from results of confirmatory maximum likelihood factor analyses and from the differential predictability of the factors with regard to various criteria. It is concluded that at least six factors are needed to account for behavior consistencies at the highest level of the personality hierarchy.