This paper aims to describe the construction and validation of a new instrument for measuring cognitive styles the Cognitive Style Inventory (CoSI) é–– that is particularly useful in an organizational context. Three successive studies are conducted to validate and cross-validate the Cognitive Style Inventory. The internal consistency of the Cognitive Style Inventory is high. Factor analyses confirm the existence of four different cognitive styles. To examine convergent and discriminant validity, the following measures are used: the Myers-Briggs Type Indicator (MBTI), the Life Orientation Test (LOT), and a Likert-scale version of Rotters Internal-External (I-E) locus of control scale. Substantial support is found for the instruments convergent and discriminant validity. Future research and practical implications are discussed.