Abstract We report some experiments that were concerned with the now familiar hypothesis that short-term memory and information processing draw upon a common pool of scarce resources. The results of two series of experiments were more consistent with the hypothesis that the resources that support short-term memory and information processing do not overlap and develop independently of each other. In Experiments 1–4, children's performance on four reasoning problems (class inclusion, conservation, probability judgment, and transitive inference) was found to be stochastically independent of their short-term memory for the critical background facts on these problems. Age changes in reasoning and short-term memory also proved to be independent. It was found in the second series of experiments that certain manipulations which affect the accuracy of children's reasoning do not affect short-term memory, and conversely. In Experiments 5–7, manipulations that affected the difficulty of information processing on class-inclusion and transitivity tasks did not affect short-term memory on these same tasks. In Experiments 8 and 9, manipulations that affected short-term retention of the background facts on conservation and probability-judgment tasks did not affect reasoning on these same tasks.