This paper develops an argument for the agency of objects, looking at the effects objects have on people. Groups of related objects, such as pots or metal ornaments, create stylistic universes which affect producers and users of new objects, bound by the canons of style. For an object to be socially powerful in a recognized manner, the form of the object lays down certain rules of use which influence the sensory and emotional impacts of the object. Formal properties of artifacts are influenced by the genealogy of the object class, including historical continuities and changes, and also its perceived source. The forms of objects, the historical trajectories of the class of objects and their perceived sources combine to have social effects on people, shaping people as socially effective entities. Britain's incorporation into the Roman Empire between 150 BC and AD 200 provides an excellent case study through which to look at the changing corpora of objects, which had continuities and changes in form, a set of subtle attributions of sources and a complex range of social effects. KEY WORDS: effects; form; Roman Britain.My attempt in this article is to explore what might be called an object-centered approach to agency. It is often assumed that society is created and reproduced through the actions of human agents who are shaped and constrained by the broader society in which they live. For the prehistorian, the active human subject is a problematical entity, but artifacts are often abundant, although not totally unproblematical as we shall see. There are a number of strands of thought within archaeology and outside which explore the effects that things have on people and I would like to use these to start thinking about the obligations objects place upon us when they are operating as a group. I shall use the incorporation of Britain into the Roman Empire as a brief case study within which to explore these ideas a little more. Periods of change are important in bringing out the relationships