Interventions are needed to increase colorectal cancer screening (CRCS) uptake. Narratives may have advantages over didactic information. We tested different narratives for increasing CRCS intentions and behaviors, and examined their mechanisms of influence. We randomized 477 unscreened adults 50–75 years old to one of three groups: CRCS information only (1) or CRCS information plus a photo and text narrative of a CRC survivor (2) or CRC screener who did not have cancer (3). Photos were tailored on participants’ sex, age group, and race/ethnicity. Participants completed online surveys before and after intervention exposure, and 1-, 6-, and 12-months follow-up. Thirty percent of participants completed CRCS. Narrative conditions (vs. information only) were negatively associated with intention, but also positively influenced intentions through greater emotional engagement. Survivor (vs. screener) narratives were positively associated with CRCS, and had mixed effects on intention–positively through emotional engagement and negatively through self-referencing engagement to self-efficacy. Survivor narratives elicited more negative affect, which had positive and negative influences on intention. Continued research using path models to understand the mechanisms of narrative effects will inform theory development and message design. Additional measurement evaluation is needed to adequately capture and then compare the effects of different components of narrative engagement.