A number of recent studies have revealed that taking part in a sail-training-based Adventure Education Programme elevates youths' self-esteem. Across two studies, we sought to examine the extent to which youths' sense of belonging contributed to this increase in self-esteem. Study 1 revealed that participants who completed the voyage showed an increase in self-esteem from the first to the last day of the voyage. Partial correlation revealed that group belonging made a unique contribution to this change. Study 2 replicated Study 1 and, further, demonstrated that the relationship between group belonging and self-esteem was not a function of self-efficacy or group esteem. Such findings suggest that an important contributing factor to the benefits of sail-training interventions is their potential to satisfy psychological needs, in this case the need to belong.