The Teachable Moment (TM) model suggests that there are certain times when an individual is especially ready to change behavior and thus, especially open to receiving messages about behavior change. According to the TM model, experiences that jointly 1) increase risk perceptions, 2) prompt concordant emotional responses, and 3) impact self-concept may offer a powerful motivational context for promoting behavior change. Further, tailoring smoking cessation interventions on TM components may increase the salience of health messages. The TM model was used to examine desire to quit smoking among family members of lung cancer patients. Further, the relationship between desire to quit and engagement with and reactions to self-help smoking cessation materials was examined. Participants were family members of lung cancer patients recruited for a randomized controlled trial testing a counseling intervention for smoking cessation. Study results indicate that components of the TM model were related to desire to quit in family members of lung cancer patients. Specifically, increased perceived risk, negative self image, and high subjective norm for quitting were related to high desire to quit. Nonwhites were more likely to have a high desire to quit than whites. There was a significant interaction between worry and gender, such that women with low worry were less likely to have a high desire to quit than were men and women with high worry. Findings on engagement with and reactions to materials were mixed. Engagement with materials was not related to baseline desire to quit, but was related to positive reactions to the materials. Those with a higher desire to quit were more likely to report that the information in the tailored booklet applied to them, and was new to them, interesting, trustworthy, and moving. Finally, family members with a higher desire to quit were more likely to say that the information in the booklet make them want to quit smoking. Evidence from this initial study indicates that the TM model provides a strong conceptual framework for 1) identifying specific determinants of desire to quit among family members of lung cancer patients; and 2) developing effective tailored self-help materials for this population.