The proposed research investigates the cognitive development of decision making in children, adolescents, and adults. It is assumed that the acquisition of competencies for making decisions that are rational with respect to the individual's goals is a fundamental requisite for adaptive responses to major life decisions. Decision making is presented as a multi-stage cognitive process, requiring general and domain specific knowledge concerning the decision, strategies for acquiring new information when the available information is insufficient for an informed choice, competencies for encoding information into a representation of alternative courses of action and their consequences, and procedures for evaluating these alternatives with respect to the decision maker's goals. The experiments focus on the development of decision making from the elementary school years through adulthood. Two tasks are employed. The first is a computerized video game that requires subjects to choose between alternative gambles presented in the form of a spinner game. The second task, to be piloted in this proposal, is a simulation of patient's informed consent decision concerning alternative medical treatments.