A re-evaluation of how ethnicity is currently understood in archaeology is necessary in view of recent developments in the archaeology of identity. In this article, it will be argued that nationalism has led to an understanding of ethnicity as monolithic, denying in this way its heterogeneous nature. Since the 1920s, archaeologists working under the culture-historical umbrella have explicitly defined ethnicity on the basis of material culture, maintaining endless, and perhaps fruitless, debates. However, as anthropologists have been discussing since the 1970s, ethnicity is perhaps not about material culture, or not necessarily about material culture, but about perception. Archaeologists should consider ethnic identities as fluid and polymorphous, for multiple ethnic affiliations can coexist and overlap in the same individual. Ethnic identification(s) displayed by each individual will change depending on the circumstances, the interlocutor and the situation. In addition, archaeologists cannot study ethnic identity in isolation from other types of identifications – gender, religion, status, etc. – as all of them will be at play, ready to act (or to be hidden), on each particular occasion. These issues will be discussed in this article in relation to Iron Age Iberians.