Usability ratings of a university website by 60 students were analysed together with participant’s self-ratings of their cognitive style. The degree of users’ “rational” as well as their “intuitive” style correlated with usability evaluation scores. In particular, self-reported rational ability was connected with evaluations of Controllability, intuitive ability was related to Helpfulness scores of the interface. Thinking style significantly affects usability ratings (explaining over 9% of the ratings’ variation), which has implications for evaluations across user groups.