The Achterhoek (; ) is a cultural region and COROP area in the Eastern Netherlands. Its name (meaning "rear-corner") is geographically appropriate because the area lies in the easternmost part of the province of Gelderland and therefore in the east of the Netherlands, protruding into Germany. The Achterhoek lies at the east of the IJssel. On the other sides, it borders Germany to the southeast and the province of Overijssel to the northeast.
In 2015, the Achterhoek had a population of 389,682. The region is also called de Graafschap (Dutch for earldom, shire or county; namesake of De Graafschap in Doetinchem) because it coincides with the historical County of Zutphen. The region is predominantly rural, with much open space, forests and farms. The area around the town of Winterswijk is regarded as noteworthy. A well-known beer originates from this region: Grolsch beer was first brewed in Groenlo in 1615.
The number of inhabitants whose sole language is Achterhooks has greatly declined since World War II. People in the Achterhoek are raised with Dutch language at school and the dialect is only spoken (sometimes) at home. Partly due to immigration from outside the region and the effects of national policy, the Dutch language is having a significant impact on the dialect. Many old words have been forgotten and replaced by their Dutch-derived equivalents.
The majority of tourists visiting the Achterhoek region are from other European countries, including Germany, Belgium, Denmark, and Ireland.