A survey and new perspectives of Celtic or La Tène art from Britain is presented. Following Spratling, Celtic art is defined as ‘ornament or pattern and animal/human/supernatural images in metal and other media’. Regional and temporal variations in the type and usage of decorated artefacts are summarised. Three case studies, made of different media, are presented: metal scabbards, bone and antler weaving combs, and pottery. By asking the question ‘why decorate?’ it is argued that the decision to decorate an artefact can affect its life history, marking it out from undecorated artefacts of the same type. Rather than serving a single function, decoration was employed to serve multiple social goals throughout the Iron Age. Different forms of social expression, such as feasting, elaborate display, or weaving, are significant at any one time or place. It is argued that decorated artefacts often played a significant role in these different social arenas. Contrary to many past discussions, decorated artefacts in media other than metal are demonstrated to have been important in negotiations of social power and cosmology.