This chapter focuses on the role of group and national identity in various types of collective actions. It features the decision to take action and asks about factors that influence that decision. Thus, our perspective is from the standpoint of the decision-maker who usually represents a collectivity (group, organization, nation). The interest is less about those decision-makers' own identities and attachments than about various drivers and constraints on their decisions to act. © 2011 Springer Science+Business Media, LLC.