Social inequality refers to the inequitable distribution of social prosperity including the resource of health. The relationship between social inequality and mental health can be established by means of indicators of social inequality throughout all age groups in Germany. There are social gradients of mental health on the population level, i.e. the linear relationship between social classes or status and state of health. Fundamental determinants of health disparity are cultural, social, political, and geographical conditions, which interact with the genetic make-up and epigenetic processes. These determinants also influence the management of developmental tasks during the life course and are of utmost importance for the development of mental disorders. The maladaptation to chronic stress is at the core of health disparity. Interventions at the individual behavioral level should comprise the development of stress management and coping strategies.