Sassier is located in the mountains of rural southwest Haiti, about 10 km (6 miles) southeast of Jeremie, the capital of Grand’Anse department.

The greater Sassier area includes Sassier itself and the nearby villages of Voldrogue, Morvan, Miller, and Marcel. About 10,000 people inhabit this region, which covers about 65 sq km (25 sq miles). Roughly half the population is under 18.