Waterloo is a town in Lauderdale County, Alabama, United States. It is part of the Florence–Muscle Shoals metropolitan area, known as "The Shoals". As of the 2010 census, the population of the town was 203, down from 208 in 2000. The town and surrounding area is served by Waterloo High School and by the Waterloo Volunteer Fire Department.

Lauderdale County is a county located in the northwestern corner of the U.S. state of Alabama. At the 2020 census the population was 93,564. Its county seat is Florence. Its name is in honor of Colonel James Lauderdale, of Tennessee. Lauderdale is part of the Florence-Muscle Shoals, AL Metropolitan Statistical Area, also known as "The Shoals".