This study assessed strategy choice and information-processing differences in gifted, normal, and mathematically disabled third- or fourth-grade children. Fourteen gifted, 12 normal, and t 5 math disabled (MD) children solved 40 simple addition problems. Strategies, and their solution times, used in problem solving were recorded on a trial-by-trial basis, and each was classified in accordance with the distributions of associations model of strategy choices. Group differences were evident for the developmental maturity of the strategy mix and for the rate of verbal counting. The gifted group showed the most mature distribution of strategy choices, followed by the normal and MD groups. In terms of speed of processing, the gifted group showed a verbal counting rate that was at adult levels and less than 50% of the rate of counting for the two remaining groups, but group differences were not evident in the rate of retrieving answers from long-term memory. The results were interpreted within the context of the strategy choice model and suggested that a single dimension spanned group differences in the level of mastery of early numerical skills: the maturity of the long-term memory organization of basic facts. Finally, implications for the mental and strategic processes contributing to academic achievement are discussed.