Eyewitness testimony may be contaminated by event-related information shared by other witnesses. The present study aimed to assess the influence of a modified cognitive interview (MCI) on the detrimental effects of what is called memory conformity. Participants watched a videotaped staged event. Immediately after this, they answered 22 questions about the video out loud, either alone or with a confederate who intentionally introduced false information in her answers (i.e., 6 incorrect and 12 confabulated details). Aweek later, participants were interviewed individually about the video using either an MCI or a structured (control) interview. Results suggested that participants recalled some of the incorrect and confabulated items suggested by the confederate. Those interviewed with the MCI (vs. SI) also reported fewer incorrect details but more confabulated details previously introduced by the confederate. The potential social and cognitive mechanisms underlying the influence of the MCI protocol on the damaging effects of prior co-witness discussions are examined.