Tweng is a municipality in the district of Tamsweg, in the state of Salzburg, Austria. It lies in the Lungau, the southeastern region of Salzburg, within the Central Alps near the border with Styria.
The area is mountainous and sparsely populated, with settlement concentrated in the valley of the Taurach river. The municipality sits close to the Radstädter Tauern Pass, a long-used crossing of the main Alpine ridge, and is part of a landscape of alpine pastures and high peaks.
Tweng is one of the smaller communities of the Tamsweg district, a largely rural administrative area whose main town, Tamsweg, serves as its economic and cultural centre. Its population is small, and the local economy has traditionally been based on agriculture and, more recently, tourism connected to the surrounding mountains and nearby ski areas.