Oak Grove (originally called Fairfield) is a town in Dodge County, Wisconsin, United States.

The unincorporated community of Minnesota Junction is located in the town.

The unincorporated community of Rolling Prairie is also located partially in the town.

There were 448 housing units at an average density of 13.1 per square mile (5.1/km2).

18.0% of all households were made up of individuals, and 7.2% had someone living alone who was 65 years of age or older.