A growing body of literature is devoted to testing the reality of the “long-tail” phenomenon. This literature is mostly, if not exclusively, focused on the impact of Internet on the distribution of sales by product. However, the long tail also raises the issue of a possible change in the usual market structure of cultural industries: an oligopoly with a competitive fringe. To our knowledge, no paper addresses the following question: If the long-tail effect does exist, is it of more benefit to small or dominant publishers? The aim of this paper was to address this issue in the context of the French publishing industry. Our main findings are as follows: (1) the market concentration of the French book industry is lower online than offline and (2) the difference in concentration between the two channels of distribution tended to widen over the period 2004–2010. Strategies adopted by leading publishers on the Web do not allow them to maintain the market share obtained with bricks-and-mortar retailers. Furthermore, we show that the market share lost by dominant firms is captured by small publishers online and by medium-sized publishers in conventional stores.