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.'

Mary-Kate Olsen and Ashley Fuller Olsen (born June 13, 1986) are American actresses, fashion designers, and businesswomen. Following their acting debut as infants on the TV series Full House, the twin sisters appeared together in a variety of TV, film and video projects throughout their child and teenage years. Through their company Dualstar, the Olsens joined the ranks of the wealthiest women in the entertainment industry at a young age.

The twins were born in Sherman Oaks, California to David Olsen (b. 1953) and Jarnette (Jarnie) Jones (b. 1954). Despite being very similar in appearance, they are not identical, but fraternal twins. They have an older brother, Trent, and a younger sister, Elizabeth, as well as two half-brothers, Taylor and Jake. The twins' parents divorced in 1995; Taylor and Jake are from their father's second marriage.

Mary-Kate and Ashley's sister Elizabeth became an actress as an adult, making an acclaimed film debut in 2011's Martha Marcy May Marlene.

In 1987, at the age of six months, the twins were cast in the role of Michelle Tanner on the ABC sitcom Full House. They began filming at nine months old. In order to comply with child labor laws that set strict limits on how long a child actor may work, the sisters took turns playing the role. The Olsens continued to portray Michelle throughout the show's run, which concluded in 1995.

Ashley Fuller Olsen (born June 13, 1986) is an American actress, fashion designer, producer, author, and businesswoman.

Olsen and her fraternal twin sister Mary-Kate Olsen were born in Sherman Oaks, California to David Olsen (born 1953) and Jarnette "Jarnie" Fuller (born 1954). Despite being very similar in appearance, they are not identical. They have an older brother, Trent, a little sister, Elizabeth Olsen, and two younger half siblings Taylor and Jake from their father's second marriage. Mary-Kate and Ashley's parents divorced in 1995.

Along with Mary-Kate, Olsen was cast at the age of nine months to share the role of Michelle Tanner on the ABC sitcom Full House. The Olsens portrayed Michelle throughout the series' 1987–1995 run. In the early 1990s, the sisters established a company, Dualstar, which produced a long string of TV movies and direct-to-video releases featuring the girls. The Olsens continued to release direct-to-video films up to the early 2000s, along with starring in the 1995 feature film It Takes Two. After Full House, the sisters starred in two other sitcoms (Two of a Kind and So Little Time) and an animated series (Mary-Kate and Ashley in Action!), each of which lasted only one season. These ventures, combined with a massive array of licensing deals for their names and likenesses, made the twins phenomenally wealthy at a young age. They became co-presidents of Dualstar upon their eighteenth birthday. Following a second feature film, 2004's New York Minute, Ashley gave up acting because she didn't feel a connection to being an actress anymore. In 2009 when asked about acting again Ashley said, "Never say never." Ashley contemplated giving up fashion and going back to acting in 2009. Ashley changed her mind in 2012 as she and Mary-Kate decided to retire from acting to focus on fashion. In 2007 Mary-Kate and Ashley expressed an interest in producing movies together.