Organizational ties between political parties and interest groups are common in contemporary democracies, but little is known about the political effects of such ties. This article examines whether the strength of organizational ties between parties and interest groups affects the probability of (1) interest group influence on parties, (2) party influence on interest groups, and (3) mutual party–interest group influence in decision-making. Using novel interest group survey data from six democracies, we are the first to systematically examine the relationship between organizational ties and perceived and attributed influence across multiple policy areas. The findings indicate that one-sided influence is more likely when the actors have stronger ties but that such ties also increase the likelihood of influence going both ways. Close party–interest group relationships hence likely involve give-and-take across policy issues. These findings shed important new light on the role of parties and interest groups as intermediaries in democracies.Party–Interest Group Ties and Patterns of Political InfluencepublishedVersio