Research suggests that testimonials, or first-person narratives, influence health behavior and health-related decision making, but few studies have examined conceptual factors that may be responsible for these effects. In the current study, older adults who were due for colorectal cancer screening read a message about screening that included a testimonial from a similar other who had previously made the screening decision. We assessed participants’ identification with the testimonial character and the degree to which they found the message to be vivid. We explored associations between these factors and participants’ knowledge following the message, mood, certainty about screening, and their behavioral intentions to look for more information about screening and to have a test in the next year. In bivariate analyses, identification and vividness were both significantly, positively associated with knowledge and behavioral intentions to have screening in the next year. However, multivariate analyses revealed that only vividness remained significantly associated with knowledge and intentions to be screened.