Only in recent years have developmental psychologists begun advocating and exploring dual-process theories and their applicability to cognitive development. In this paper, a dual-process model of developments in two processing systems-an "analytic" and an "experiential" system-is discussed. We emphasise the importance of "metacognitive intercession" and developments in this ability to override experiential processing. In each of two studies of sunk cost decisions, age-related developments in normative decisions were observed, as were declines in the use of a "waste not" heuristic. In the second study, children and adolescents were presented with arguments for normative and non-normative sunk cost decisions. Following argument evaluation, participants were re-presented the original problems and a set of novel, transfer problems. Results indicated that post-argument improvements were most apparent during adolescence. Age-related improvements were most noticeable on the transfer problems. In general, the findings suggest that the ability to metacognitively intercede (i.e., reflect on arguments; inhibit experientially produced responses) emerges towards middle adolescence. However, even by the end of adolescence, in the absence of significant contextual cues and motivation, this ability is infrequently utilised.