The evolutionary synthesis of the 1930s and 1940s integrated the study of biological microevolution and biological macroevolution into the theoretically consistent and hugely productive field of evolutionary biology. A similar synthesis has yet to occur for the study of culture, and the social sciences remain fragmented and theoretically incompatible. Here, it is suggested that a Darwinian theory of cultural evolution can promote such a synthesis. Earlier non-Darwinian theories of cultural evolution, such as progress theories, lacked key elements of a Darwinian theory of cultural evolution (e.g., population thinking) that are necessary to promote a synthesis, while other contemporary theories of cultural evolution, such as memetics, make too stringent neo-Darwinian assumptions (e.g., high-fidelity replication) that are inconsistent with evidence regarding cultural transmission. Several examples are given which indicate the beginnings of an evolutionary synthesis for culture, where patterns of cultural macroevolution have been explained in terms of underlying cultural microevolutionary forces. Finally, it is argued that experimental simulations of cultural evolution can play an important role in this emerging synthesis.