Disadvantageous decision making is cited as one of the premier problems in childhood development, underlying risky behavior and causing adolescents to make poor choices that could prove detrimental later in life. However, there are relatively few studies looking at the development of decision making in children and adolescents, and fewer still comparing it with the performance trajectories of more typically developing cognitive functions. In the current study, we measured the affective decision-making abilities of children and adolescents 8- to 17-years-old using the Iowa Gambling Task (IGT; Bechara, 2007) in conjunction with a battery of established cognitive neuropsychological assessments. In contrast to the typical linear development of executive functions, affective decision-making abilities progressed in a J-shaped curve. Younger, more developmentally naive children performed better on the IGT than older, early-adolescent individuals, with performance becoming advantageous again toward the end of the teenage years. This trajectory is thought to coincide with asymmetric neural development in early adolescents, with relatively overactive striatal regions creating impulsive reward-driven responses that may go unchecked by the slower developing inhibitive frontal cortex. This trajectory is in stark contrast with the linear development of memory, speed of processing, and other cognitive abilities over the ages.