Ways of thinking: Personality affects reasoning. This paper presents an investigation testing the idea that personality affects the way people reason in a predictable way. That is to say, traits may affect the particular possibilities that individuals envisage and so, in turn, how they reason. Different traits can elicit different ways of thinking and as a result, individuals would reason better in the fields that are pertinent to their personality. We tested 94 participants with the NEO-PI-R and with a conditional inference task that was tailored based on the items in the NEO-PI-R personality test. We found, in general, that our participants reasoned better (higher rate of Modus Tollens) with the materials that were related to the personality trait in which they scored highest. Also, the participants who scored high in Extraversion or Neuroticism produced more valid inferences for the items related to their personality than those who scored low in the same trait. These results are in accordance with the principle of inferential consequences and the Mental Models Theory of Reasoning.