This study investigated the role of broad cognitive processes in the development of mathematics skills among children and adolescents. The participants for this study were a subsample of a nationally representative sample used in the standardization of the Woodcock-Johnson III Tests of Cognitive Abilities and the Woodcock-Johnson III Tests of Achievement, Normative Update (Woodcock, McGrew, & Mather, 2007). Participants were between 5 years old and 18 years old (N = 4721; mean of 10.98 years, median of 10.00 years, standard deviation of 3.48 years), and were 50.7% male and 49.3% female. Structural equation models supported the theoretical suggestion that broad cognitive processes play significant and specific roles in the development of mathematical skills among children and adolescents. Implications for school psychology researchers and practitioners are discussed.