In an incidental memory task, second, sixth, and tenth-grade students performed three orientating tasks on different subsets of items in a list of common nouns. In one condition (EPA), children judged words on the Evaluative, Potency and Activity dimensions of the semantic differential. In another condition (EEE) children made phonetic judgments. Analysis of recall scores supported the hypothesis that superiority of semantic over phonetic encoding would increase with age. However, results did not support the hypothesis that superiority of the EPA condition over the EEE condition would emerge with age as children's semantic structures become more differentiated. In fact, the two conditions did not differ at any grade. In a second experiment, a shift in recall favoring the EPA over the EEE condition was observed between tenth-graders and adults. It was speculated that in addition to dimensional independence which emerges by age 12, relatively equal weighting of dimensions within semantic structure, which may not appear until adulthood, is a necessary condition for the facilitating effect of multiple dimension encoding to occur. (Author)