People's incorrect recalls can contaminate their collaborators' performance on subsequent tasks, referred to as the social contagion of memory. Research investigating how expectations about group members' abilities and affiliations relate to such contagion has given little attention to the mechanisms underlying any differential reliance on collaborators' contributions. In two experiments, we investigated whether expectations about a collaborative partner influence social contagion and whether source monitoring was related to any differential reliance. Contagion was reduced, for both accurate and inaccurate information, when participants worked with a partner perceived to be of low as compared with high credibility. Participants also showed reduced contagion after working with an out‐group as compared with an in‐group partner. These findings indicate that partner characteristics influence whether the information generated during a collaborative task is encoded and/or relied upon later. Expectations about potentially problematic sources can motivate resistance to misinformation through careful monitoring of partner contributions. Copyright © 2014 John Wiley & Sons, Ltd.