We develop a spreading activation model, which we call the category activation model, to predict where within a category structure consumers are likely to position a subcategory that they have created to accommodate a new hybrid product. Based on this model, we hypothesize that the probability that an individual will position a new category subordinate to a particular category i is proportional to the relative number of categories that are already subordinate to i. We report the results of two studies that support this hypothesis and provide evidence that accessibility is an underlying mechanism.