Twenty-seven kindergarten subjects were trained on two different double classification matrix tasks to determine whether they were hierarchically related. Prior behavioral analyses had shown one task to be simpler than the other. It was assumed that, in hierarchical transfer relationships, one order of task acquisition is more favorable than others. Thus, it was predicted that learning the simpler task, then the complex, was the "optimal" learning sequence. The study was designed so that this optimal order could be compared with non-optimal orders. Results indicated: (1) that subjects who learned in optimal order learned the more complex task in fewer trials than subjects who learned in the reverse (non-optimal) order; and (2) subjects in the reverse order group acquired the simpler task in process. These are in accord with the hypothesis that the two tasks are hierarchically related. It was suggested that acquisition of complex cognitive skills may be a matter of learning specific relevant prerequisites rather than of entering a "stage" of development. (Author/TL)