Xavier THIERRY has a PhD in demography and was until recently deputy director of the coordination team of the French birth cohort launched in 2011 which recruited about 18 thousands babies (Étude longitudinale française depuis l'enfance - www.elfe-france.fr/en).
   
In 1997, he defended a thesis in demographic analysis on the formation of unions and births outside marriage. Then he was appointed permanent researcher at the French demographic institute (INED, Paris).
   
His articles have a strong statistical and methodological component. An expert in the French statistical system, he takes a keen interest in administrative matching. He pioneered the compilation of immigration statistics in France based on residence permits issued to foreigners. He was responsible on estimates of inflows of foreign population published each year by its institute.
   
His research activities have focused successively on international migration and family reunification, single-parent families, mortality by marital status, breastfeeding, learning at school and mental health, childcare arrangements and the socialization of children under different perspectives.
   
He is editor-in-chief of the Ined website - www.ined.fr

During his stay at Penn for fall 2023, he is planning to work on living and household arrangements among children whose parents are separated in industrialized countries. He is also interested in making a new orientation on population issues in relationship to the warming climate.