Forty-six intellectually precocious (M age = 74 months) and 250 intellectually typical (M age = 75 months) children were administered a standardized working memory battery, speed of processing measures, and tasks that assessed skill at number line estimation and strategies used to solve simple and complex addition problems. Precocious children had an advantage over same-age peers for all components of working memory, and used a more mature mix of strategies to solve addition problems and to make number line estimates; there were no group differences for speed of processing. Many of the advantages of the precocious children on the number line and addition strategy tasks were significantly reduced or eliminated when group differences in working memory were controlled. Individual differences analyses revealed that each of the three components of working memory contributed to different aspects of skilled performance on the mathematics tasks.