The manuscript examines the influence of contextual factors on whether and for whom a colon polyp diagnosis might be a teachable moment, as indicated by engagement with a proactively delivered intervention. Baseline and 8-month follow-up data were analyzed from a two-site behavioral intervention trial with patients in Massachusetts and North Carolina, USA who had recently undergone polypectomy for pre-cancerous colon polyps and were randomized to a behavior change intervention condition (N=591). Intervention "buy-in" was used as an indicator of response consistent with the polyp identification serving as a teachable moment. Cancer worry, personal risk, health-related self-identity and other sociodemographic factors were tested to predict intervention buy-in. As predicted, those who were most worried about colon cancer were most likely to engage in the intervention. One indicator of personal risk, number of risk behaviors, was significantly and negatively associated with buy-in. Predictors of intervention buy-in and cancer worry were not consistent. We recommend that expanded measures of affect and health-related self-identity should be considered in future research to understand the motivational potential of health events for increasing engagement in effective behavior change interventions.