  Political and advertising campaigns increasingly exploit social networks to
spread information and persuade people. This paper studies a persuasion model
to examine whether such a strategy is better than simply sending public
signals. Receivers in the model have heterogeneous priors and will pass on a
signal if they are persuaded by it. I show that a risk neutral or risk loving
sender prefers to use public signals, unless more sceptical receivers are
sufficiently more connected in the social network. A risk averse sender may
prefer to exploit the network. These results still hold when networks exhibit
homophily.
