Reactive Approach Motivation (RAM) theory proposes that the personal uncertainty arising from motivational conflict causes anxiety, and that anxiety draws people to extremes because extremes activate approach-motivated states that automatically downregulate anxiety. Five new studies consolidate existing evidence for the RAM view of uncertainty-related threats and reactive extremism. In Studies 1–3, religious, idealistic, and RAM reactions after agentic, communal, and mortality threats were most extreme when threat-relevant goals had been implicitly primed to create motivational conflict. In Study 4 uncertainty predicted extreme reactions only if goal conflict had been experimentally manipulated. In Study 5 personal uncertainty uniquely predicted lifestyle extremes among undergraduates whose educational goals were conflicted by a labor disruption at their university. Results converge on the conclusion that uncertainty-related threats cause defensively extreme RAM reactions only if they arouse personal uncertainty about active goals. Results suggest that policies and programs to support the prosocial and/or nonextreme goals, ideals, and identifications of at-risk people would reduce their motivation for antisocial extremism.