Rensselaer is a city located along the Iroquois River in Marion Township, Jasper County, Indiana, United States. The population was 5,859 at the 2010 census, up from 5,294 at the 2000 census. The city is the county seat of Jasper County. Saint Joseph's College is located just south of the city limits.

Jasper County is a county located in the U.S. state of Indiana. As of 2020, the population was 32,918. The county seat is Rensselaer.