The analysis of the development of social complexity among the peoples of the Mediterranean coast of the Iberian Peninsula has broadly followed the general trends of European and North American archaeology. This chapter proposes a new synthesis of the processes of change between the Late Bronze Age and the Roman conquest in the northern regions of the Iberian culture area. First, it considers Godelier's structural Marxist evolutionary hypothesis, which is compatible with Johnson and Earle's model but hard to substantiate with the available data. According to Godelier's hypothesis, the transformation of an early Iron Age Great Man into a Big Man society requires some conditions. Then, the chapter examines role of culture contact and trade with colonial societies such as Phoenician, Etruscan and Greek. The chapter concludes that foreign trade was instrumental for indigenous elites to acquire and consolidate their privileged status; it probably did not play a significant role as a cause for social change.