Targeting families at risk for hereditary and familial forms of cancer is an important component of disease prevention and supportive care. Family characteristics can influence individual health behaviour and psychosocial outcomes. This study explored the role of religious (RWB) and existential well-being (EWB) on family communication, individual psychosocial outcomes, and screening practices in families with Lynch syndrome, also known as hereditary nonpolyposis colon cancer. Participants (N = 123, 34 families) were individuals with Lynch syndrome associated cancers and first-degree relatives at risk of inheriting an identified deleterious mutation. Analyses controlled for age, gender, cancer diagnosis, and network size. Higher family RWB was associated with increased depression (p < .05) and avoidant cognitions (p < .05). Higher family-level EWB was related to decreased depression (p < .001). Higher family EWB promoted utilization of faecal occult blood testing (p < .01), and family communication about genetic counselling and testing (p < .01). Analyses pointed to individual effects of EWB above and beyond family-level effects. Specifically, individuals with higher EWB than their family had higher perceived risk for colorectal cancer (p < .05), communicated disease risk information with their family more often (p < .05), and were more likely to undergo colonoscopies (p < .05). Participants with lower EWB than their family had higher cancer worry (p < .01) and depression (p < .001). Results emphasize the multidimensional nature of spiritual well-being and salience of existential well-being in promoting healthy behaviours in families with Lynch syndrome. Findings indicate the importance of assessing individuals within the context of their family network and being aware of family characteristics, such as EWB and RWB, which may impact individual adjustment to disease risk. Interventions considering family-level factors may provide efficient pathways to improving psychosocial outcomes, screening practices, communication about disease risk and genetic testing, and cancer prevention.