There were 6,196 households of which 44.5% had children under the age of 18 living with them, 67.8% were married couples living together, 9.1% had a female householder with no husband present, and 19.8% were non-families. 17.6% of all households were made up of individuals and 7.7% had someone living alone who was 65 years of age or older. The average household size was 2.85 and the average family size was 3.24.
In the city the population was spread out with 32.2% under the age of 18, 6.8% from 18 to 24, 29.4% from 25 to 44, 21.7% from 45 to 64, and 10.0% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 92.5 males. For every 100 females age 18 and over, there were 89.6 males.
The median income for a household in the city was $58,508, and the median income for a family was $66,476. Males had a median income of $47,716 versus $27,478 for females. The per capita income for the city was $22,779. About 1.4% of families and 2.1% of the population were below the poverty line, including 1.8% of those under age 18 and 2.7% of those age 65 or over.
A skate/bike park, The Derby Skate Park, located at 424 E. Market, is one of the most recent additions to the city’s park system. The park is located at the site of the old municipal pool.
The school district also operates a sixth grade center, a middle school, an alternative high school, and Derby Senior High School.
St. Mary's is a Pre-K through 8th grade Catholic school.