<p>This paper presents an evolutionary model of patriotism. The state interacts with a population of citizens who may differ in their levels of patriotism, reflecting how much they care about the state. Citizens’ patriotism is subject to evolutionary pressure in the long run. Under complete information, if the state’s payoff function exhibits strategic complementarity, patriotism can emerge through evolution. In the presence of incomplete information, however, patriotism fails to thrive. Despite this, if citizens can costlessly disclose their levels of patriotism to the state in a truthful but potentially imprecise manner, full information revelation can be achieved under certain monotonicity conditions—one of which can be derived from the supermodularity of the interaction between the state and citizens—thus allowing patriotism to evolve in a manner similar to the complete information case.</p>