The following sources of evidence are discussed in order to examine the component parts — in terms of primary traits — of Eysenck's psychoticism scale, which he refers to as a ‘superfactor’ but which is here viewed as a composite or complex of primary traits. Factor analytic studies by the author and by Barratt & Kline not only showed agreement as to factor composition but also each found a psychoticism factor and supply evidence as to the question posed. Additionally (a) a correlational study by the author and (b) a study by Eysenck supply evidence. Thus from factor analytic and correlational evidence a high P scorer possesses these traits: impulsiveness, lack of cooperation, oral pessimism, rigidity, low superego controls, low social sensitivity, low persistence, lack of anxiety and lack of feelings of inferiority. Of the three main ‘superfactors' advocated by Eysenck — neuroticism (N), extraversion (E) and psychoticism (P) — the evidence indicated that psychoticism was the least univocal.