This study examines the relationship between loneliness, health, and mortality in older adults using data from the Health and Retirement Study (HRS) in the U.S. It finds that feelings of loneliness are associated with increased mortality risk over a six-year period. The study investigates potential mechanisms, including social relationships, health behaviors, and health outcomes. While social relationships and health behaviors did not fully explain the effect of loneliness on mortality, health outcomes such as depressive symptoms, self-rated health, and functional limitations moderately explained it. Cross-lagged panel models showed that loneliness both affects and is affected by depressive symptoms and functional limitations over time, with marginal effects on self-rated health. The study highlights that loneliness is a risk factor for morbidity and mortality in older adults, with health outcomes serving as potential mechanisms. The findings suggest that loneliness influences health, which in turn affects mortality risk. The study also notes that health behaviors alone may not fully explain the mortality effects of loneliness, indicating the need for further research into the biological and psychological mechanisms linking loneliness to health outcomes and mortality. The study contributes to the growing literature on the negative health impacts of loneliness in older adults.This study examines the relationship between loneliness, health, and mortality in older adults using data from the Health and Retirement Study (HRS) in the U.S. It finds that feelings of loneliness are associated with increased mortality risk over a six-year period. The study investigates potential mechanisms, including social relationships, health behaviors, and health outcomes. While social relationships and health behaviors did not fully explain the effect of loneliness on mortality, health outcomes such as depressive symptoms, self-rated health, and functional limitations moderately explained it. Cross-lagged panel models showed that loneliness both affects and is affected by depressive symptoms and functional limitations over time, with marginal effects on self-rated health. The study highlights that loneliness is a risk factor for morbidity and mortality in older adults, with health outcomes serving as potential mechanisms. The findings suggest that loneliness influences health, which in turn affects mortality risk. The study also notes that health behaviors alone may not fully explain the mortality effects of loneliness, indicating the need for further research into the biological and psychological mechanisms linking loneliness to health outcomes and mortality. The study contributes to the growing literature on the negative health impacts of loneliness in older adults.