While "lasting effects" of outdoor experiences have been suggested, few empirical studies have traced influences more than one year after the experiences. This study examines the written responses of 67 Japanese expedition participants who took part in a British-organized overseas youth expedition 20-23 years ago, to investigate their perception of the influences of the experiences through a retrospective approach. The findings show that the vast majority of respondents (99%) considered their expedition experience to be significant in their lives, and 96% answered that this experience had influenced their present selves. The study also identified perceived key elements of the expeditions that generated the influences, such as a diverse group of people, age of participation, and the natural environment. The findings yielded two implications for practice. Organizers of overseas youth expeditions should carefully consider the social and cultural dimensions of the hosting nations as well as those of the participants. Reflection and sharing after the experiences seem to help the learning to grow, and it is worthwhile for practitioners to encourage networking and sharing among participants after programmes are completed.