Summary: It has been conjectured that the peer-based recommendations associated with electronic commerce lead to a redistribution of demand from popular products or "blockbusters" to less popular or "niche" products, and that electronic markets will therefore be characterized by a "long tail" of demand and revenue. In this paper, we develop a novel method to test this conjecture and we report on results contrasting the demand distributions of books in over 200 distinct categories on Amazon.com. Viewing each product as having a unique position in a hyperlinked network of recommendations between products that is analogous to shelf position in traditional commerce, we quantify the extent to which a product is in ‡uenced by its recommendation network position by using a variant of Google's PageRank measure of centrality. We then associate the average level of network in ‡uence on each category with the inequality in the distribution of its demand and revenue, quantifying this inequality using the Gini coe¢ cient derived from the category's Lorenz curve. We establish that categories whose products are in ‡uenced more by recommendations have signi…cantly ‡atter demand distributions, even after controlling for variations in average category demand, the category's size and measures of price dispersion. Our empirical …ndings indicate that doubling the average in ‡uence of recommendations on a category is associated with an average increase in the relative demand for the least popular 20% of products by about 50%, and a average reduction in the relative demand for the most popular 20% by about 12%. We also show that this e¤ect is enhanced when there is assortative mixing in the recommendation network, and in categories whose products are more evenly in ‡uenced by recommendations. The direction of these results persist across time, across both demand and revenue distributions, and across both daily and weekly demand aggregations. Our work o¤ers new ideas for assessing the in ‡uence of networks on demand and revenue patterns in electronic commerce, and provides new empirical evidence supporting the impact of visible recommendations on the long tail of electronic commerce.