We consider a society in which each agent has one unit of a resource to allocate between two activities. Agents are organized in a social network, and each activity generates complementarities between neighbors. We find multiplicity of equilibrium for high intensity of interaction, and we characterize equilibria in terms of specialization and polarization. Overall, results reveal the crucial role played by network geometry. The results also suggest that the structure of the social network should be taken into account for the design of a public policy in favor of a specific activity.