Le Grand-Serre (French pronunciation: [lə ɡʁɑ̃ sɛʁ]; Arpitan: Sèrra) is a commune in the Drôme department in southeastern France.

The Galaure flows west through the northern part of the commune, then forms part of its north-western border.

The nearest communes are Marcollin and Saint-Clair-sur-Galaure, both in the Isère department.

2 schools are located in the commune, a primary school and a high school.