The municipality is located in the Thal district, in the Gulden valley between the second and third Jura mountain chains. It sits on the route over the Passwang Pass, the Wasserfallen crossing and the Schelten Pass. The municipality covers the entire Gulden valley, as well as the Lobisei canyon, which connects to the Balsthal valley. It is the largest municipality, in terms of area, in the Canton of Solothurn. It consists of the villages of Mümliswil and Ramiswil as well a number of hamlets and individual farm houses.