Casti-Wergenstein or Casti-Vargistagn is a former municipality in the Viamala Region in the Swiss canton of Graubünden.

[3] Casti-Wergenstein was created in 1923 through the union of the formerly independent municipalities of Casti and Wergenstein.

Over the same time period the amount of forested land has increased by 44 ha (110 acres).

[8][9] Before 2017, the former municipality was located in the Schams sub-district, of the Hinterrhein district, after 2017 it was part of the Viamala Region.

[14] The historical population is given in the following chart:[15] In the 2015 federal election the most popular party was the SVP with 36.7% of the vote.

The percentage of the vote received by the FDP increased sharply from 2.0% in 2011 to 21.7% in 2015, as did the SP from 5.1% to 10.8%.

Of these, a total of 10 people worked in 4 businesses in the primary economic sector.

[20] In 2015 the average cantonal, municipal and church tax rate in the municipality for a couple with two children making SFr 80,000 was 4.2% while the rate for a single person making SFr 150,000 was 18.3%, both of which are much higher than average for the canton or nationally.

However, since World War I, German has grown to the point that it is about evenly divided between Romansh-speaking and German-speaking population.