is a city in Sedgwick County, Kansas, United States. Formerly known as El Paso, it is a suburb of Wichita. The population was 17,807 at the 2000 census. Derby was recently named one of the "10 Best Towns for Families" by Family Circle magazine.
According to the United States Census Bureau, the city has a total area of 7.5 square miles (19.3 km²), of which, 7.4 square miles (19.3 km²) of it is land and 0.13% is water.