After a PhD in political science, Cossart became assistant professor in sociology (University Lille 3, CeRIES). She is now member of the Institut Universitaire de France. Her current research focuses on the historical sociology of participatory democracy. She is particularly interested in the genealogy of deliberative devices. At Harvard, she will work on the history of New England town meetings. She has published numerous articles and two books : Vingt-cinq ans d’amours adultères. Correspondance sentimentale d’Adèle Schunck et d’Aimé Guyet de Fernex. 1824–1849 (2005) and Le meeting politique. De la délibération à la manifestation (2010). She will be in residence from March to July 2013.
