This article focuses on military role identity by assessing the relations between demographic variables and warrior and peacekeeper role identities and by examining the potential influence of these role identities on self-esteem, organizational commitment and organizational citizenship behavior (OCB) in a cross-national sample. A questionnaire was distributed to military members in four participating countries: Belgium, Estonia, Canada and the Netherlands (n = 831). The findings show that demographic variables (i.e., age, gender, marital status and unit) are related to military role identity, and that military role identity predicts self-esteem, organizational commitment and OCB. In particular, multiple regression analyses demonstrate that peacekeeper role identity predicts self-esteem, organizational commitment and OCB, whereas warrior role identity only predicts organizational commitment and OCB, and further, that peacekeeper role identity is a stronger predictor of the outcome variables measured. The theoretical and practical implications, including providing commanders with information to assess their units’ mindsets, and mechanisms to improve self-esteem, commitment, OCB, are discussed. Finally, the limitations of this study and its potential for future research are described.