Wonder Lake is a former census-designated place (CDP) in McHenry County, Illinois, United States.

As of the census[3] of 2000, there were 7,463 people, 2,674 households, and 1,986 families residing in the CDP.

There were 2,997 housing units at an average density of 479.7 per square mile (185.2/km2).

The racial makeup of the CDP was 96.22% White, 0.28% Black or African American, 0.21% Native American, 0.59% Asian, 1.38% from other races, and 1.31% from two or more races.

19.5% of all households were made up of individuals, and 5.2% had someone living alone who was 65 years of age or older.