Purpose Social environments exert an important influence on health behaviors, yet evidence from rural‐specific contexts is limited. This study explored how social relationships influence health‐related behaviors among midlife and older rural adults at increased risk of chronic disease. Methods Seventeen focus groups were conducted with 125 sedentary, overweight/obese adults (aged 40‐91 years) residing in “medically underserved” rural Montana towns in 2014. Groups were stratified by age (40‐64 and ≥65) and gender. Transcripts were examined thematically using NVivo software according to social influences on diet, physical activity, and tobacco use. Analyses were conducted in 2015‐2016. Results Attitudes and actions of family members and friends were key influences on health behaviors, in both health‐promoting and health‐damaging ways. In these small, isolated communities, support from and accountability to family and friends were common facilitators of behavior change and maintenance. However, expectations to conform to social norms and traditional gender roles (eg, caregiving duties) often hindered healthy lifestyle changes. Conclusions These findings suggest that health behavior interventions targeting adults in rural settings need to consider and, if possible, integrate strategies to address the impact of social relationships in both supporting and sabotaging behavior change and maintenance.