--- - |2+ Objective Previous studies on the relationship between interpersonal trust and social movement participation have largely focused on the simple link, without attention to the interaction between trust and aspects of the political context. This study investigates this contingent effect of two types of interpersonal trust (ingroup and outgroup trust) on social movement participation. Method The data are drawn from the World Values Survey 6th wave and country‐level Macro Indices from 41 countries. We use multilevel modeling (random coefficient model) to test the contingent effect of trust. Results The results reveal a positive association between outgroup trust and protest participation, moderated by both functioning institutions and state repression. Meanwhile, ingroup trust is not significantly associated with protest participation. Conclusion This contingent theory of trust could reconcile previous inconsistent empirical findings and explain why trust may have an insignificant or weaker effect on social movement participation in some contexts. - 'Social Science Quarterly, Volume 99, Issue 4, Page 1484-1495, December 2018. '