This research investigates how threats to people’s ingroups promote ways of thinking and behaving that benefit these groups (ingroup prosociality). Drawing on terror management theory and other relevant literature, I propose that threats promote ingroup prosociality, and that threats play an important role in explaining why members of collectivistic societies (e.g., Eastern) tend to exhibit more ingroup prosociality than members of individualistic societies (e.g., Western). Three experimental studies isolated effects of threats on outcomes I propose reflect ingroup prosociality: holistic versus analytic types of cognitive and social orientations (Study 1), upholding status orders in groups (Study 2), and promoting the legitimacy of power in groups (Study 3). To experimentally manipulate threat, participants wrote about either a threatening or non-threatening situation. In the group studies (2 and 3), the threat situation was also part of the task itself. Study 1 provides some support for increased ingroup prosociality when threatened, and some evidence for differences by culture and type of threat. Though results generally suggest that Americans respond more ingroup prosocially than Indians, they do not provide compelling evidence of consistent cross-cultural patterns as predicted. Study 2 provides only minimal support for threat increasing adherence to status orders. Study 3 provides a great deal of support for threat increasing promotion of the legitimacy of power structures, and results suggest especially strong responses among high-status participants with low-status partners. For each study, I also address some results in the opposite direction predicted. Taken together, the results only somewhat support my proposed ingroup prosociality worldview theory. Alternatively, patterns in results suggest that threatened ingroup members may be motivated to preserve their self-esteem and reduce their anxiety. Though this self-serving explanation is consistent with terror management theory, it is not consistent with the ingroup prosociality worldview initially proposed. Overall, the results provide evidence that threat (1) affects both behaviors and orientations (many proposed to reflect ingroup prosociality), which warrant consideration together as defensive responses to threats, and (2) increases promoting the legitimacy of power based on status in some situations. I discuss limitations, implications for theory and potential leadership interventions, and directions for future work.