Résumé : This research concurrently investigated the effectiveness of three established bias-reducing interventions (i.e., positive affirmation, secure attachment, and cognitive dissonance) in the wake of the Paris and Brussels terror attacks. Using frequentist and Bayesian analyses, Study 1 ( N = 1,676), launched within days of the attacks, found that compared to a control condition, the interventions did not significantly improve intergroup attitudes. Instead, the data showed strong support of the null hypotheses that there were no intervention effects. Proximity to the attacks did not moderate the effect. Study 2 ( N = 285) reexamined the effects of the three interventions 2.5 years after the attacks, generally replicating the pattern of findings in Study 1. Together, this research highlights the challenge of intergroup bias reduction following terror attacks. We conclude by discussing several recommendations for how psychological interventions could play a more impactful role in contexts of heightened conflict.