World’s Longest Happiness Study Continues After 88 Years The longest-running study on adult development, initiated in 1938 by Harvard University, has tracked hundreds of participants for over eight decades. It found that close relationships are the strongest predictors of happiness and health in later life, rather than wealth, intelligence, or even good genes. Loneliness emerged as a significant risk factor for poor well-being, while the quality of relationships, especially marriages, acted as a buffer against life’s stressors.

• The Harvard Study of Adult Development, started in 1938, is the world’s longest study on happiness and adult life.
• The study initially compared privileged Harvard students with underprivileged Boston teenagers and later expanded to include women and children.
• After 88 years and multiple generations of researchers, the study found that close relationships are the best predictors of health and well-being in old age.
• Satisfying relationships, particularly strong connections with friends and family, are linked to longer, happier, and healthier lives.
• Loneliness and social isolation are significant risk factors for poor health and premature death.
• The quality of relationships, rather than the quantity, is crucial for well-being.
• Satisfying marriages can buffer the negative effects of poor health on happiness.