The aim of this study was to obtain a better understanding of the personal experiences and interpersonal factors that influence the performance of small military teams deployed in an extreme and isolated environment for an extended period of time. Twelve members of the Danish Sirius Patrol operating in Greenland in 6 two-person teams were evaluated over the course of a 7-week Fall and a 23-week Spring dogsledge journey by means of a bi-weekly rating form and debriefing interviews. Ratings of positive affect were significantly higher than negative affect over the course of the journeys (p = .03); adaptive cognitive and behavioral coping strategies and generally compatible interpersonal relationships were recorded. The importance of appropriate communication for team effectiveness was emphasized, including expectations about their work together and personal goals. The findings also demonstrated the negative influence of unexpected interpersonal events in the home environment on team member relationships and work performance. Applications for long-duration space exploration are discussed.