We demonstrate with computational simulation scenarios how social environments and individual behavior coevolve and how fundamentally different macro-effects emerge, when separate micromechanisms are combined. Our framework considers social interactions among agents on a spatial grid or in networks. In the Prisoner’s Dilemma, neither imitation of more successful strategies nor the migration to more favorable locations can promote cooperation. However, when both microscopic mechanisms are combined, they cause the segregation of cooperators and defectors, and the self-organization of cooperative clusters on the macro-level. These are robust to randomness, while cooperation may break down in a ‘‘globalized society’’. The implications for the evolution of norms and institutions are discussed.