The influence of gender on the social context in which work performance takes place is considered. Women in single and mixed-gender polar expedition groups reported concern for the welfare of a teammate as a significant stressor. All-male teams exhibited higher levels of competitiveness and a lesser tendency to talk about their feelings. Excerpts from expedition debriefing interviews illustrate gender-related patterns noted in extreme environments. Application of these findings for the better selection, training, and performance of mixed-gender space crews is examined. A case study approach to conducting research on crew performance is recommended, and strategies for dealing with confidentiality are discussed.