In recent years, evolutionary psychologists and anthropologists have debated whether ethnic markers have evolved to solve adaptive problems related to interpersonal coordination or to interpersonal cooperation. In the present study, we add to this debate by exploring how individuals living in a modern society utilize the accents of unfamiliar individuals to make social decisions in hypothetical economic games that measure interpersonal trust, generosity, and coordination. A total of 4603 Danish participants completed a verbal-guise study administered over the Internet. Participants listened to four speakers (two local and two nonlocal) and played a hypothetical Dictator Game, Trust Game, and Coordination Game with each of them. The results showed that participants had greater faith in coordinating successfully with local speakers than with nonlocal speakers. The coordination effect was strong for individuals living in the same city as the particular speakers and weakened as the geographical distance between the participants and the speakers grew. Conversely, the results showed that participants were not more generous toward or more trusting of local speakers compared with nonlocal speakers. Taken together, the results suggest that humans utilize ethnic markers of unfamiliar individuals to coordinate behavior rather than to cooperate.