### Question
What is the definition of child?


### Answer
The definition of **child** is as follows in *42 U.S.C. § 290ff*:

> an individual through the age of 21 years

#### Citation:
  - *42 U.S.C. § 290ff*
  - Heading: **CHAPTER 6A-PUBLIC HEALTH SERVICE > SUBCHAPTER III&ndash;A-SUBSTANCE ABUSE AND MENTAL HEALTH SERVICES ADMINISTRATION > Part E-Children With Serious Emotional Disturbances**

