This paper develops a model of demand, pricing and advertising in the presence of social learning via word-of-mouth communication between friends. In the model consumers must receive information about a monopolist's product in order to consider purchasing it. The presence of word-of-mouth is not sufficient for demand to be more elastic and prices to be lower compared to an informed population. I derive the comparative static results of connectivity, mean-preserving spread of friendships, and clustering of friends on prices. The optimal targets for advertising are not, generically, the individuals with the most friends.

We develop a model of market entry under social learning through word of mouth (WOM). The success of an entrant depends on consumer awareness generated via WOM, modeled as a percolation process on a random graph. The likelihood of an entrant gaining significant awareness depends on network structure, characterized by the first three factorial moments of the degree distribution. We identify three pricing equilibria: blockaded, deterred, and accommodated entry. The model demonstrates that increased network density can shift equilibria from blockaded to deterred and eventually to accommodated entry. Numerical simulations suggest that consumer surplus may be nonmonotonic with respect to network density. Additionally, if incumbents can charge personalized prices based on consumers' connectivity, they may optimally set lower prices for highly connected consumers.