Human behaviour affects health outcomes. Behavioural and social sciences investigate the cognitive, social, and environmental drivers and barriers that influence health-related behaviours. Behavioural evidence on what influences behaviours at the individual, community, and population level can improve the design of policies and programmes, communications, and products and services aimed at achieving better health for all. Applying behavioural and social sciences requires a multidisciplinary approach and the adoption of theory, methods, research, practical tools and techniques drawn from psychology, sociology, anthropology, communications, marketing, economics, systems thinking and design thinking, among others. Behavioural and social sciences evidence can contribute to and complement other public health efforts that focus on the non-medical factors that influence health outcomes.