While numerous studies have documented an association between mainstream media trust and mainstream media use, only little is known about potential causal mechanisms underlying the association. We theorize that selective exposure, social influence, and the reinforcing spirals model offer three possible mechanisms that may underlie the association. These possibilities were studied using random intercept cross-lagged panel models and latent curve models on a four-wave panel data set (n = 3,540). For mainstream media, the results show an asymmetrical reinforcing spiral, in which the effect of mainstream media trust on use can be considered as one of yielding maintenance, while the impact of media use on mainstream media trust to a limited degree is in line with the notion of a spiral gradually (though inconsistently) increasing trust over time. We also find that use of right-wing alternative media consistently and sometimes robustly leads to decreasing mainstream media trust.