Cristina Bicchieri is the S. J. P. Harvie Professor of Social Thought and Comparative Ethics, Professor of Philosophy and Director of the Philosophy, Politics and Economics programme at the University of Pennsylvania. She is a leader in the fields of rational choice and social norms. She has published six books and hundreds of articles. Her work on social norms shows how changing collective expectations radically changes behaviour. UNICEF is adopting her work on social norms in its campaigns to eliminate practices that violate human rights.