This research explores the possibility that when people receive sequential persuasive messages about different issues, the trustworthiness of the source of an early (prior) message can influence people’s motivation to process a subsequent (target) message. Participants were presented with a target persuasive message from a source of ambiguous trustworthiness. Preceding this message, participants received a message about a different issue from a source unambiguously high or low in trustworthiness. When primed to focus on similarities, participants showed greater processing of the target message when the prior source was low rather than high in trustworthiness (assimilation). When primed to focus on dissimilarities, participants showed the opposite effect (contrast). As expected, however, these effects were particularly likely to manifest for low need for cognition individuals, who are not otherwise inclined to engage in extensive processing. High need for cognition individuals engaged in extensive processing regardless of the prime and prior source manipulations.