The term refers to the latchkey of a door to a house. The key is often strung around the child's neck or left hidden under a mat (or some other object) at the rear door to the property. The term seems to first appear in a CBC radio program called "Discussion Club – Topic: How War Affects Canadian Children" in 1942, due to the phenomenon of children being left home alone during World War II, when the father would be enlisted into the armed forces and the mother would need to get a job. Given that the "Discussion Club" participants are all familiar with the term and allude to it being in colloquial usage, it likely predates 1942. In general, the term latchkey designates "those children between the ages of five and thirteen who care for themselves after the school day until their parents or guardians return home".
More specifically for their purposes, the San Marino (CA) Public Library has defined a Library Latchkey Child as "one who on a regular basis is required by their parents or guardian to remain at the public library for extended periods of time after school in lieu of day care. 'Regular basis' is defined as three or more days per week. 'Extended period' is defined as two or more hours per day" (American Library Association 12).
The term latchkey kid became commonplace to describe members of Generation X, who according to a 2004 marketing study, “went through its all-important, formative years as one of the least parented, least nurtured generations in U.S. history.” Latchkey kids were prevalent during this time, a result of increased divorce rates and increased maternal participation in the workforce, at a time before childcare options outside the home were widely available. These latchkey children, referred to as "day orphans" in the 1984 documentary, To Save Our Children to Save Our Schools, mainly came from middle or upper-class homes. The higher the educational attainment of the parents, the higher the odds the children of this time would be latchkey kids.
The effects of being a latchkey child differ with age. Loneliness, boredom and fear are most common for those younger than 10 years of age. In the early teens, there is a greater susceptibility to peer pressure, potentially resulting in such behaviors as alcohol abuse, drug abuse, sexual promiscuity and smoking. The behaviors might stem from "unspent energy, peer pressure to misbehave, or hostility because of the lack of appropriate adult attention". However, some children experience positive effects, such as an early development of self-reliance, adaptation to difficult situations, and a desire to contribute to a visible need in the household.
Socioeconomic status and length of time left alone can bring forth other negative effects. In one study, middle school students left home alone for more than three hours a day reported higher levels of behavioral problems, higher rates of depression, and lower levels of self-esteem than other students.