This paper addresses the issue of whether four of the learning styles instruments currently available are of sufficient psychometric quality to warrant their continued use either for research or educational purposes. Four instruments, which purport to measure learning styles, were selected for review. Criteria for selection were based in part on the frequency of references in the professional literature and discussions with several adult educators who have had considerable experience with the assessment of learning styles. The four instruments chosen were the Myers-Briggs Type Indicator, the Kolb Learning Style Inventory, Canfield's Learning Styles Inventory, and Gregorc's Style Delineator. The paper is divided into six sections. Following the first section, which introduces the study, each of the next four sections consists of a detailed critique of the four learning styles instruments selected for review. Each critique follows the same format and includes a description of (1) the practical features of the test, administration, scoring, and other considerations; (2) characteristics of the manual, including how information is reported and what test interpretation information is provided; (3) characteristics of the test including norms, reliability, validity, and its overall quality; and (4) a summary statement that focuses on the reviewer's personal decision regarding the use of the test. The paper closes with a listing of research questions that need to be explored and some suggestions for improving the measurement of learning styles. (KC)