Human behavior is a key determinant of health. Consider the leading risk factors for the top causes of death and disabilities: underweight mothers and children; unsafe sex; high blood pressure; smoking; alcohol abuse; unsafe water, poor sanitation and hygiene; high cholesterol; indoor smoke from solid fuels; iron deficiency; and overweight. In poor countries, two risk factors--childhood underweight and unsafe sex-- contribute more to the loss of healthy life-years in the world than all diseases and injuries in high-income countries, and they can be addressed through effective behavior-change interventions. Our standard approaches have had limited success in persuading people to adopt healthier behaviors. Information alone does not usually lead to behavior-change. New and growing evidence points to a different way of approaching behavior-change, and not only in the health sector. The challenge is to adapt this new knowledge and use it in design of reforms for UHC.