Health promotion and preventive action in the context of public health interventions for highly prevalent, long-term conditions such as cancer are rarely geared toward the family as a whole. Yet family members, as cancer cosurvivors, must manage their own substantial stress and multiple caregiving responsibilities and often constitute a critical nexus between individual patients and clinicians. We drew on 2 examples of cancer cosurvivorship from 2 different health service contexts, the United States and Finland. A systemic approach in public health is needed to support family members who not only have to confront the meaning of long-term conditions such as cancer but also may have to manage concurrent social life challenges and stressors such as economic hardship. (Am J Public Health. Published online ahead of print May 19, 2016: e1-e7. doi:10.2105/AJPH.2016.303178).