There are neurons in the hippocampus that become active only when an animal is near a particular location in a specific environment. The activity of some of these units is known to be governed by the configuration of a small set of discrete landmarks. In order to respond in this fashion, these neurons must, in effect, be able to recognize particular locations. A model of this recognition process is described which is able to make quantitative predictions about how the response of these place-field units varies as properties of the environmental landmarks are manipulated. Computer simulations of the model show that it is consistent with the available quantitative data. These simulations also predict large, characteristic changes in place-field location and size with manipulations of the environmental landmarks. Comparison of this kind of prediction with actual experiments will serve as a test of the validity of the model.