Although in general we have little or no difficulties in speaking and thinking about organisations, describing the empirical reality of organisations is far from easy. Where should we look for organisations? How should we study them? Organisations are markedly elusive. They cannot be treated as empirical entities. What you perceive, when "looking" at organisations, are artifacts (buildings, machines) and behaviour (linguistic and other forms). But neither artifacts, nor behaviour are "organisation-like" in themselves. What is needed, therefore, is something that relates artifacts and behaviour to create a more or less coherent whole. Such a relation is a representation, shared, at least in part, by a number of interacting actors. It is the representation that gives both artifacts and behaviour their meaning. A representation is a mental activity of an actor. It should be clear that we take representations not as referring to some mental activities act upon ('symbols"), but as a specific type of mental activity, also referred to as "cognition", possibly only found in humans. To define cognition only in terms of (the manipulation of) 'symbols' is begging the question (petitio principii), as the symbol implies precisely that mental activity that has to be explained if we want to understand what cognition is. If anywhere, therefore, an organisation resides in the mental activities of the actors. This does not necessarily imply, however, that all the actors involved must represent an organisation in the same way.