Objectives: This study aims to identify the psychosocial factors affecting on happiness among the general population in South Korea. Methods: This cross-sectional study was conducted using the multiple-stratified random sampling on the Korea Census of 2005. In October 2009, investigators conducted 15-minute face-to-face interviews with 1,500 South Korean volunteers ranging from 30 to 69 years old with no history of cancer. The questionnaire included socio-demographics, stress levels, coping strategies, social support, SOC, and happiness levels. Results: The multivariate analysis identified that married persons were more likely to be happy than those who were not married, respondents who had a higher score of stress and SOC were less likely to be happy, and those who had a higher score of social support from family were more likely to be happy. Conclusions: Interventions designed to increase happiness may need to include activities to control stress and promote social support from family.