While sisters of breast cancer patients are at increased risk for developing breast cancer due to their family cancer history and age, little research with first-degree relatives of cancer patients has focused solely on sisters. To address this issue, the current study examined sisters screening and health behaviors and the predictors of these behaviors. In accordance with the Parallel Processing Theory, the current study assessed the relationship of cognitive and emotional factors to screening and healthpromoting behaviors among sisters of breast cancer patients. In addition, this study expanded upon the Parallel Processing Theory by also examining the relationship of interpersonal factors to screening and healthpromoting behaviors. One-hundred-twenty sisters of breast cancer patients from 89 different families completed questionnaires assessing perceived risk of breast cancer, perceived response efficacy of mammography, diet, and exercise, breast cancer worry, trait anxiety, involvement in sister's cancer care, satisfaction with the sister relationship, mammography screenings, physical activity, and amount of fruits and vegetables consumed. Findings indicated that cognitive, emotional, and relational factors were significantly related to mammography screenings, but not to diet or exercise. Specifically, response efficacy for mammography screening was positively related to mammography screening; while trait anxiety and involvement in sister's care were negatively related to mammography screening. Additional analyses indicated that breast cancer worry had a curvilinear relationship with mammography screenings, such that no relationship was seen for women with lower breast cancer worry; for women with higher levels of worry, the greater their worry, the less likely they were to obtain mammography screenings. Breast cancer worry was also found to interact with involvement in care, such that among women less involved in their sister’s care, greater breast cancer worry was associated with having fewer mammography screenings. However, for women more involved in their sister’s care, greater breast cancer worry was associated with having more mammography screenings. Future research should further assess whether a teachable moment exists related to the family member’s cancer diagnosis and treatment during which to encourage the FDR to engage in screening healthpromoting behaviors.