The family returned to France after the Edict of Saint-Germain in 1562, and settled at Crest in Dauphiné, where Arnaud Casaubon, Isaac's father, became minister of a Huguenot congregation.
Keluarganya kembali ke Prancis setelah dekret dari Saint-Germain pada 1562, dan menetap di Crest di Dauphiné, di mana Arnaud Casaubon, ayah Isaac, menjadi menteri suatu kongregasi Huguenot.