This study examines the relationship between loneliness, health, and mortality in a nationally representative sample of 2,101 adults aged 50 and over from the 2002 to 2008 waves of the Health and Retirement Study. The researchers found that feelings of loneliness were associated with increased mortality risk over a six-year period, and this effect was not fully explained by social relationships or health behaviors but was modestly explained by health outcomes such as depressive symptoms, self-rated health, and functional limitations. Cross-lagged panel models showed that loneliness affected and was affected by depressive symptoms and functional limitations over time, and had marginal effects on later self-rated health. The findings contribute to the growing body of literature indicating that loneliness is a risk factor for morbidity and mortality and point to potential mechanisms through which this process works.This study examines the relationship between loneliness, health, and mortality in a nationally representative sample of 2,101 adults aged 50 and over from the 2002 to 2008 waves of the Health and Retirement Study. The researchers found that feelings of loneliness were associated with increased mortality risk over a six-year period, and this effect was not fully explained by social relationships or health behaviors but was modestly explained by health outcomes such as depressive symptoms, self-rated health, and functional limitations. Cross-lagged panel models showed that loneliness affected and was affected by depressive symptoms and functional limitations over time, and had marginal effects on later self-rated health. The findings contribute to the growing body of literature indicating that loneliness is a risk factor for morbidity and mortality and point to potential mechanisms through which this process works.