Objectives Studies generally find no relationship between economic deprivation and terrorist activities, leading to the conclusion that economic conditions have no role in the emergence of terrorist movements. The present paper challenges this conclusion. It argues that collective deprivation affects participation into terrorism, but in different directions depending on the ideology of terrorist movements: far-right terrorism should mobilize more under times of collective deprivation while far-left terrorism should mobilize more under times of collective improvement. Methods I tested this hypothesis on the PIRUS database about domestic terrorists (N = 1295) in the United States from 1948 to 2016. I analysed whether the proportion of far-right (versus far-left) terrorists in a given year depends on collective deprivation in the US, operationalized through long-term recession of the income and long-term growth of inequality. Results Hierarchical logistic regression analyses confirmed that far-right terrorism mobilizes more under periods of long-term economic deprivation, while far-left terrorism mobilizes more under improving economic conditions. Besides, the effect of collective deprivation appears to be of socio-tropic nature: it is especially determinant at the national level, rather than at the state or individual level. In contrast, results do not support the view that Islamist terrorism is affected by collective deprivation. Conclusions The study challenges the view that economic conditions have no role in triggering terrorist mobilization. The differential effect of collective deprivation on farright and far-left terrorism is compatible with system-justification and backlash theories. Besides, the findings suggest that collective deprivation affects radicalization at an early phase rather than the offending phase.

Contrary to a popular belief, research has generally found no relationship between collective economic deprivation and the rise of radical political movements. On the other hand, various studies show that collective economic deprivation generates societal surges of conservatism. I therefore hypothesize that the absence of a relationship between collective deprivation and radical movements covers up opposite effects of collective deprivation depending on the ideology of radical movements: Reactionary (i.e., conservative radical) movements should mobilize more in times of collective deprivation, whereas revolutionary (i.e., progressive radical) movements should mobilize more in times of collective improvement. This paper tests this hypothesis via a new database measuring the level of mobilization of French radical organizations from 1882 to 1980. Statistical analyses confirm that collective deprivation, operationalized by long‐term economic recession and long‐term growth of inequality, increases the mobilization of reactionary movements and decreases the mobilization of revolutionary movements. These results contradict the view that economic conditions have no role in triggering radical movements and support recent development of system justification theory implying that ideology matters in the explanation of collective action.