Preadolescence is a stage of human development following early childhood and prior to adolescence. It generally ends with the beginning of puberty, but may also be defined as ending with the start of the teenage years. For example, dictionary definitions generally designate it as 10–13 years. It may also be defined as the period from 9–14 years. One can also distinguish middle childhood and preadolescence - middle childhood from approximately 5–8 years, as opposed to the time children are generally considered to reach preadolescence (age 9–14 years).

Preadolescence can bring its own challenges and anxieties and unlike most of the preceding phases, crucial elements of preadolescence are starkly different for boys and girls.

The point at which a child becomes an adolescent is defined by the onset of puberty or by the beginning of the teenage stage. Adolescence is also viewed as ending with the teenage stage. However, in some individuals (particularly females), puberty begins in the preadolescence years, and adolescence may extend a few years beyond the teenage years in others (typically males). Studies indicate that 'the onset of puberty has been one year earlier with each generation since the 1950s.'