Gallier was born January 5, 1949, in Nancy, France, and holds dual French and American citizenship.
He earned his baccalauréat at the Lycée de Sèvres in 1966, and a degree in civil engineering at the École Nationale des Ponts et Chaussées in 1972.
[1] He then moved to the University of California, Los Angeles for his graduate studies, earning a Ph.D. in computer science in 1978 under the joint supervision of Sheila Greibach and Emily Perlinski Friedman.
At Pennsylvania, he was promoted to full professor in 1990, gained a secondary appointment to the Department of Mathematics in 1994, and directed the French Institute of Culture and Technology from 2001 to 2004.
[1] Gallier's most heavily cited research paper, with his student William F. Dowling, gives a linear time algorithm for Horn-satisfiability.