People from different cultures vary in cognition, emotion, and behavior. We explore cultural differences in a tagging system. We developed a model of cultural differences and performed a controlled empirical study with American and Chinese subjects to investigate questions that arise from the model. American and Chinese subjects differed in many ways: the number and types of tags they applied; the extent to which they applied suggested tags or entered new tags of their own; and how often they applied tags that originated from a different culture. Our results are consistent with theories of cultural differences between Asian and Western cultures. Our findings suggest new opportunities and mechanisms for shaping user behavior to produce useful tag repositories.