Episodic memory and episodic future thinking appear to be fundamentally linked, sharing many commonalities that have led numerous theorists to claim that they rely on the same neural system and develop simultaneously. On the other hand a number of striking temporal asymmetries have also been observed in the way that we think about the past and the future: events in the future appear to be valued more than those in the past, feel closer in subjective time and elicit stronger emotions. The aim of this thesis was two-fold in that it considered both of these areas of the mental time travel literature. Developmental research into the link between past and future mental time travel is limited therefore, Studies 1a and 1 b examined 3-to 10-year-olds' past and future narratives. The findings suggest that the proposed link between episodic past and future thinking may be more complex among children than adults and raise doubts over the manner in which previous studies have interpreted the relations between narratives for past and future events. Studies 2a-3c explored the developmental profile of temporal asymmetries in mental time travel. Until now a developmental account of temporal asymmetries in value, emotion and subjective temporal distance was absent; therefore Studies 2a-3c make original contributions to knowledge. Over the course of these studies, appropriate tasks and methodologies were identified for examining such asymmetries in children and adolescents. The evidence emerging from these studies suggests that the type of task used (hypothetical versus real event tasks) in developmental studies is crucial, whilst these different asymmetries did not appear to emerge at the same stage in development. These studies offer a comprehensive and wide-ranging developmental consideration of mental time travel, not only examining the similarities in the same way as previous developmental studies, but also considering the temporal asymmetries in mental time travel.