Ansó is a town and municipality in the province of Huesca, in the Aragon region of northern Spain. It lies in the Pyrenees near the border with France, in the valley of the Ansó river, a traditional and relatively isolated mountain area of the Aragonese Pyrenees.
According to the 2004 census (INE), the municipality had a population of 523 inhabitants. The municipality covers more than the town of Ansó itself: it also includes the smaller settlement of Fago.
Ansó is known for its well-preserved traditional stone architecture and its historic old town, which retains a distinctively Pyrenean character. The town has served as the administrative centre of its surrounding valley, and its economy has traditionally been based on livestock farming and related rural activities.