Four validation studies of different versions of the Approaches to Studying Inventory (ASI) were performed by means of exploratory and confirmatory factor analysis. Six samples of undergraduate students participated (N = 4,038), drawn from different bachelor programs in selected university college departments. The results gave limited support to the 18-item ASI originally promoted by Gibbs et al. in 1988, whereas a modified version of the 32-item edition showed acceptable psychometric properties, as did two shortened versions of the Approaches and Study Skill Inventory for Students (ASSIST). A restructured "quick-and-easy" 18-item ASI emerged as reasonably valid and robust, and can be recommended as a research instrument and a practical evaluation tool in higher education. Considerations related to shortening the ASI are also discussed. (Contains 9 tables and 1 footnote.)