Current rule-utilization research indicated that subjects successively tested multiple conceptual rules, available from natural preexperimental experience, to solve a sorting task. Prior results suggested that older subjects were more efficient in utilizing rules and shifting to unused rules, possibly due to the availability of more conceptual rules at higher age levels. The experimental groups consisted of third, fourth, sixth, ninth graders, and college students. Each of the five groups contained 16 subjects. The rule-utilization procedure was applied to each group. The procedure contained a multitrial, card sorting task. The feedback given at the end of each trial was limited to the correctness of the entire card sort and did not provide information on the correctness of the sorting for any individual card. All subjects in each group were run until they used both bidimensional rules (the conjunctive and the inclusive-disjunctive rule), or until a limit of 30 trials was reached.