This study examined the ability of preschool children to process and use conceptual category information in a disrcimination learning task. A total of 60 boys and girls between the ages of 2 1/2 and 4 years completed a 3-choice discrimination learning task. On each of 12 trials, a child was presented with three magazine photographs: one of an animal, one of an item of food, and one of an item of clothing. The positive instance on every trial was a member of the same conceptual category (either food or animal). Half of the children were initially given an example of the kind of stimulus which would be reinforced and half had to learn the conceptual rule through trial and error. Subsequently the children were given sorting, labeling, and concept identification tasks. Between 70%-100% of children at all ages used the category information to solve the discrimination learning task. Children who had been required to discover the conceptual rule independently did as well as those who had not. Even the 2 1/2-year-olds demonstrated the ability to spontaneously recognize and utilize a conceptual rule. Certain performance measures indicated an improvement over age. It was suggested that this progression is primarily related to the speed with which a conceptual strategy is adopted rather than the ability to use the conceptual information. This paper discusses a number of methodological issues involving the clarification of tasks for child subjects. (Author/MS)