Underlying concepts such as "superordinate goals" and "common group identity" is the idea that we humans would achieve peaceful relationships if we adopt a common goal and shared identity. A number of classic (e.g., Sherif, 1966) and contemporary (e.g., Kunst et al., 2015) lines of research support this perspective. Building on this tradition, peace psychologists might view the global coronavirus pandemic that rapidly spread in 2020 as an opportunity to unite humanity: we are all in this together, against a common "foe." However, rather than achieving unity in confrontation with this "common foe," humankind has entered a new phase of intense rivalry and conflict, both within and between nations.To those who have closely followed the impact of global warming and the climate crisis on intergroup relations around the world, the influence of the coronavirus pandemic has not come as a surprise. The enormous destructive power and serious danger posed by global warming could serve to unite humankind and lead us to adopt coordinated and united policies to deal with this challenge. But this has not happened. In practice, global warming is also associated with fractious politics and international conflicts.Clearly, research and applied psychologists need to give closer attention to the conditions in which a common threat, such as the coronavirus pandemic or global warming, actually does result in better cooperation between groups. Under some conditions a global threat can lead to greater conflicts and even mutual radicalization, with groups and nations pushing one another to extremes (Moghaddam, 2018). Of course, radicalization does not take place in a vacuum-individuals and groups always radicalize against other (real and imagined) forces. For example, White supremacists in Europe and North America radicalize against (real or imagined) enemies who threaten their White Christian national identities, just as Islamic fundamentalists radicalize against (real or imagined) Westerners attacking Islamic communities. Similarly, under certain conditions threats such as the coronavirus pandemic and global warming result in mutual radicalization and intergroup conflicts, not cooperation and peace. Two of the most important factors influencing this process are leadership and citizenship.Leaders can in important ways influence the adoption of superordinate goals and common group identities. This was noted by Sherif (1958) and continues as a theme in 21st century research (Hogg et al., 2012). At the time of the coronavirus pandemic, the leaders of China, Russia, and the United States have in different ways undermined the possibility of the pandemic being used as a superordinate goal for the world. Similarly, these leaders have worked against a coordinated global effort to combat global warming. The destructive and constructive role of leaders should receive more attention from peace psychologists.Second, peace psychologists need to give more attention to the psychological characteristics that citizens need to develop to recognize and be...