This chapter discusses the process of behavioral health adaptation to isolated, confined, and extreme (ICE) environments, with primary focus on National Aeronautics and Space Administration (NASA) astronauts and countermeasures provided to those astronauts by the Behavioral Health and Performance group at NASA’s Lyndon B. Johnson Space Center. Adaptation is a process occurring continually in every walk of life. Organizations with employees who live and work in an ICE environment because of their job have a responsibility to support those employees in order to maximize successful psychosocial adaptation and job performance. Many ICE environments, such as foreign peacekeeping and space missions, involve more than one nationality. Deployed military service members and astronauts often work closely with people from other nations. Multiple factors influence the degree of stress felt by crews in ICE environments.