Recent developments in computer networks have driven the cost of distributing information virtually to zero, creating extraordinary opportunities for sharing product evaluations. We present pricing and subsidy mechanisms that operate through a computerized market and induce the efficient provision of evaluations. The mechanisms overcome three major challenges: first, evaluations, which are public goods, are likely to be underprovided; second, an inefficient ordering of evaluators may arise;

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... d, the optimal quantity of evaluations depends on what is learned from the initial evaluations. (JEL D70, D83, H41, LI5) Subjective evaluations by others are a valuable tool for consumers who are choosing which products (o buy or how to spend their time. For example, we read magazines devoted to product evaluation before purchasing cars and appliances. We ask our friends and read reviews by professional critics when selecting movies and restaurants. Professional colleagues recommend articles. Product evaluations are provided by friends, other consumers, brokers, and frequently even product suppliers. Yet the use of evaluations is severely limited by today's production, collection, and distribution systems. The production of evaluations is costly, requiring money or time for people to