During the last two decades, product labeling has become an increasingly used policy tool, particularly with respect to the provision of health and environmental information. Theory holds that the flow of information among market participants plays a critical role in the efficient operation of markets. This paper explores the role of product labeling policy in ameliorating two potential market deficiencies: asymmetric information and costly search behavior. Practical considerations for the design and implementation of labeling policy and of labeling research are explored.