The Rational-Experiential Inventory REI (Pacini and Epstein, 1999) is a self-administered test comprising two scales measuring the attitude of respondents towards two thinking styles respectively referred to as the rational and the experiential thinking styles. Two validation studies were conducted using a new French-language version of the REI. The first study confirms the validity of the French translation. The second study, which is concerned with the REI's construct validity, assesses the questionnaire's capacity to discriminate between a group of smokers and a group of non-smokers. Both studies give generally satisfactory results. In particular, the advantages of using the two-dimensional REI rather than the better known Need For Cognition scale (Cacioppo & Petty, 1982) are made quite clear.