Objectives: Despite declining trust in government institutions, political scientists have observed increasing political participation across activities, including grassroots lobbying. We argue that higher levels of trust in the state political system as a whole—diffuse political trust—and in state legislatures—specific political trust—should increase the likelihood that citizens contact their state legislators about policy matters because higher levels of trust tend to correlate with believing that the policy-making process produces equitable political outcomes. Methods: We use observational data from a nationally representative survey sample taken in 2015. Results: We find mixed results: whereas diffuse political trust predicts participation in grassroots lobbying at the state level, specific political trust does not. Conclusion: This finding implies that more general feelings of political trust exert greater influence on grassroots lobbying behavior than do more institution-specific indicators of trust.