Social epidemiology is a sub-discipline of epidemiology explicitly investigating social determinants of population distributions of health, disease, and well-being. Persistent pattern of social inequalities in health in spite of the broad improvement in the physical environment over the last centuries necessitated the development of this field as an approach to understand disease etiology that incorporates social experiences as more direct determinant of health. Social epidemiology incorporates theories, measurement tools, and techniques from a wide variety of other social sciences. A population perspective, the social context of behavior, contextual multilevel analysis, a developmental and life-course perspective, and general susceptibility to disease are the most important guiding concepts in social epidemiology.