Champasak (or Champassak, Champasack – Lao: ຈຳປາສັກ [tɕàmpàːsák]) is a province in southwestern Laos, near the borders with Thailand and Cambodia. It is one of the three principalities that succeeded the Lao kingdom of Lan Xang. As of the 2015 census, it had a population of 694,023. The capital is Pakse, but the province takes its name from Champasak, the former capital of the Kingdom of Champasak.
Champasak is bordered by Salavan province to the north, Sekong province to the northeast, Attapeu province to the east, Cambodia to the south, and Thailand to the west. The Mekong River forms part of the border with neighboring Thailand and contains Si Phan Don (‘Four Thousand Islands’) in the south of the province, on the border with Cambodia.
