Readlyn is a city in Bremer County, Iowa, United States. The population was 845 at the time of the 2020 census. It is part of the Waterloo–Cedar Falls Metropolitan Statistical Area. The city is known for its culture surrounding the "Grump", a title of honor and area folklore character inspired by a real resident of Readlyn in the early 20th century.

Bremer County is a county in the northeastern part of the U.S. state of Iowa. As of the 2020 Census, the population was 24,988. Its county seat is Waverly. The county was named for Fredrika Bremer, a Swedish feminist writer.