Putnam’s (2007) constrict claim states that ethnic diversity has serious consequences for social cohesion, making people distrustful and leery. The present contribution extends this claim by including political cynicism and trust as side effects of diversity. Moreover, we nuance this claim by considering citizens’ social-ideological attitudes as moderators of diversity effects. Using a Dutch nationally stratified sample (N = 628), we showed that both objective and perceived diversity were associated with more political cynicism and less trust, but only for those high in right-wing attitudes (i.e., social dominance orientation and particularly authoritarianism). Furthermore, only political cynicism was a unique predictor of greater populist party support. Implications for the ongoing debates on the rise in diversity and populist parties are discussed.