Many cancer survivors and their relatives remain at risk for medical complications due to genetic and/or lifestyle risk factors. Although some patients and family members are prompted by a cancer diagnosis to address modifiable risk factors (e.g., smoking, poor diet) others are not. Unfortunately, behavioral cancer research has not yet identified the factors that predict motivation to change health-related behaviors, and thus clinicians are limited in their ability to determine which individuals are likely to implement these changes. This study tests the hypothesis that behavior change among cancer patients and their first-degree relatives is influenced by beliefs about the cancer, based on the Common-sense Model of Illness Representation. In specific, the study will look at the association between health behaviors (e.g., diet, smoking, exercise) and two types of cancer-related beliefs: beliefs about the cause of the cancer, and beliefs about the influence of different health behaviors on the course of cancer. This brief assessment study, therefore, has the potential to shed light on an important area of primary and secondary cancer prevention.