Why are norms enforced? According to functionalist accounts, norms are useful to society at large, while rational choice theory suggests that norms are useful to those who enforce them. The "Emperor's Dilemma" suggests an alternative possibility -- that members of a group may enforce obligations to act in ways that few if any group members actually want or need. Familiar examples of this popular enforcement of unpopular norms range from the comic to the tragic: fawning admiration for a highly prestigious but incomprehensible scholar (whose brilliant new ideas presumably cannot be grasped by intellectual lightweights); the "politically incorrect" whose censure affirms the moral standing of those who are sufficiently indignant; spiraling conflicts sustained by those who privately wish for peace but retaliate because they think it is "honorable" and expected of them. Research on "pluralistic ignorance" and the "illusion of transparency" shows that we sometimes overestimate support for social norms. What remains unexplored is whether people not only publicly comply with privately unpopular norms but also enforce these norms. Our hypothesis is that individuals enforce norms that they privately question in order to seek social approval; thus they camouflage their true opinions by public displays of false sincerity. Is this "illusion of sincerity" sufficient to trap a population in a social equilibrium in which unpopular norms are popularly enforced? What factors increase the likelihood of this social trap? We plan to use game theory, agent-based modeling, and laboratory experiments to develop and test a dynamic model of self-enforcing norms. Formal theory is needed to carefully disentangle the tautological knot posed by norms that are enforced -- not because of an interest in others' compliance -- but because of the very social pressure that enforcement decisions produce. A formal model is needed to investigate these dynamics and to identify the processes by which a population comes to be trapped in this equilibrium and by which it might escape. We will then use laboratory experiments to test under controlled conditions the hypotheses suggested by the theory.