This paper focuses on a century of interaction between a colonial agent (Rome) and an indigenous people (known in classical texts as the Laietani) who inhabited the area before the arrival of the conquerors. It investigates how contact between the two societies may be detected in the archaeological record, and, where possible, what changes in local culture resulted. The first part, which presents the archaeological sites of the Cabrera de Mar valley and its material culture, documents the contacts over time between those that occupied the valley and those who arrived from the Italian peninsula. A number of indices of such contacts are considered: architecture, construction techniques, imported pottery, epigraphy, and the monetary system. The second part considers whether it is possible to detect in the valley not only cultural contact but also cultural change.