The traditional conception of a thin market based on transactions volume remains relevant in many agricultural markets but does not adequately frame emerging thin market issues. As non-price means of pricing goods becomes more common, some cash commodity markets have become residual markets. In some of these markets, not only the volume of transactions but also the representativeness of transactions to those on the related contract market is an important issue. This paper develops a concept of thin markets that accounts for this dimension of market thinness and proposes a research agenda related to this topic.