A mathematical model is presented in which we can understand and discuss the behaviour of concurrent computing agents such as interconnecting hardware modules, operating system components and parallel programs. It is shown that it is natural to represent computing agents in a "value-passing" framework rather than by using a global store. Proof techniques involving computation induction which allows us to reason about psuLesses and the agents they represent in a concise manner are also given, together with a uniform method of modelling the scheduling of a number of computing agents. Two scheduling techniques involving this method are presented and they are shown to be equivalent. This result is used in a final example where we use the process model to produce two equivalent denotational semantics for a concurrent programming language involving path expressions.