This thesis examines the art of Babylonia, Iran and Bactria after the Macedonian conquest, from c.330 to c.100 BC, in light of current developments in archaeological theory of cultural interaction. In order to illustrate the character and scale of these interactions, the thesis presents a discussion of iconographic material ranging from architectural ornament and sculpture to minor arts. Chapters II-IV discuss the material from each site, highlighting regional characteristics and differences between media. Chapters V-VII use three cross-sections to examine cultural interaction visible in material used for different social functions (‘spheres’). The ‘sphere of gods’ discusses religious architectural ornament and iconography, and the implications for our interpretation of cult in Babylonia, Iran and Bactria in this period. The ‘sphere of kings’ considers ruler representation and the physical appearance of ‘royal space’ while the ‘sphere of citizens and subjects’ discusses material made and used by the wider populace. Macedonian rule and the influx of settlers to Babylonia, Iran and Bactria developed networks of exchange, transmission and transformation creating ‘visually multi-lingual’ societies. The adoption of new artistic influences did not replace all existing traditions or necessarily infringe ethnic identities. There was selective adoption and adaptation of iconography, styles and forms to suit the new patrons and contexts. This cultural co-existence included some combinations of features from different artistic traditions into individual compositions, emphasising how visual languages were not closed-off, rigidly defined or static. Patrons were not confined to using the visual language associated with their ethnicity or current location. There was flexibility of use and meaning, which may present a useful model in the study of other areas of cultural interaction in the Hellenistic period.