There is a rise in the use of global and cross-organizational teams in engineering projects, consequently issues such as team coherence and commitment have gained growing attention in engineering literature and practice (Davies & Hobday, 2005). Creating effective cooperation in project teams which consist of individuals from various countries, organizations and with various expertises is difficult. Apparently, merely placing people together does not create an effective team (Salas, Burke & Cannon-Bowers, 2000; Ruiz Ulloa & Adams, 2004) as both organizations and the individuals working in these organizations have their own subset of goals, norms, jargon, modus of operandi and culture. Research in social and organizational psychology and management shows that identification with the own team or organization can strongly influence the cooperation processes between teams, through in-group versus out-group feelings (De Drue & van Vianen, 2001; Williams, 2001; Chatman et al., 1998). However, there is still little insight in how organization identity changes within international and cross-organizational military engineering teams. For the purpose of gaining more insight in this issue, we undertook a longitudinal exploratory case study of individuals who were part of a cross-organizational military engineering projects which was deployed to Mazar-e Sjarif (MeS) in Afghanistan. The case study showed a change in the strength of various identities of these individuals during the project. Additionally a workshop was organized to explore possible factors which affect changes in identity strength. After analyzing the results of this workshop six variables were indicated, these are: having negative feelings, knowledge of one another, working towards the same goal, duration of a mission, being ‘stuck’ in the same situation and whether or not one feels a personal connection with the people in the group.