The A*Midex Foundation is launching its fourth call for applications for the Chair of Excellence programme. The ambition of Aix-Marseille University and its partners, through this programme, is to attract (and stabilise) on the Aix-Marseille site exceptional teachers, teachers-researchers and researchers of international standing, on structuring projects contributing to the strategy of the Aix-Marseille site. The A*Midex Foundation regularly issues calls for proposals for this programme, with a limited number of projects approved each year (1 to 3 new projects per year).