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.

There is substantial empirical evidence showing that peer effects matter in many activities. The workhorse model in empirical work on peer effects is the linear‐in‐means (LIM) model, whereby it is assumed that agents are linearly affected by the mean action of their peers. We develop a new general model of peer effects that relaxes the linear assumption of the best‐reply functions and the mean peer behavior and that encompasses the spillover, conformist model, and LIM model as special cases. Then, using data on adolescent activities in the United States, we structurally estimate this model. We find that for many activities, individuals do not behave according to the LIM model. We run some counterfactual policies and show that imposing the mean action as an individual social norm is misleading and leads to incorrect policy implications.