In the present study, albino rats were given discrimination training in a modified Skinner Box. During this training several schedules of SD—SR pairings were presented; differential effects of this training were measured during extinction, which also involved a further scheduling of the R—Sr pairings. The results of the study showed that the animals were discriminating, and that SD functioned as Sr during extinction. However, there was no consistent evidence that a moderate degree of intermittence in reinforcement during either discrimination or extinction phases had favorable effects on secondary reinforcing properties. There remains the possibility that there are real but small effects which could be detected only by much more extensive experimentation.