Third Culture Kids (TCKs) are the children of expatriates who live in a foreign country for their work. Such 'work' may include occupations in the military, diplomatic corps, mission field, non-profit sector, education, and corporate business.

TCKs inhabit three distinct, yet interrelated, cultures: the first being a child's country of origin and/or parental culture of which they hold a passport but may or may not have been born in; the second being the host country in which a child is currently living; and the third culture belonging to the community within the second culture that a TCK most identifies with in terms of a shared lifestyle and meaning.

International schools often represent the "third" culture to TCKs because these campuses share several common characteristics that TCKs come to understand as "normal": teachers, staff and students are multi-culturally diverse, and there is a high turnover of the student body. Additionally, while the content of children's stories in the international school community may differ, their experience is nonetheless universally understood much like a familiar script in which they, and their parents, often find comfort, security, and a sense of shared identity.

Being a TCK is both a privilege and a burden. For parents, there is probably no other life decision so wrought with uncertainty and apprehension as the one to relocate their children abroad, whether temporarily for work or as emigrants. For children repatriating to their home or passport country to attend university, the experience can be one of cultural imbalance, frustration, and isolation in the realization that their "normal" highly mobile, cross-cultural life is very different from that of their college peers.

And yet, TCKs are often coined "citizens of the future" because they acquire cross-cultural skills and experience diverse opportunities at a young age, with many viewed as ideal leaders of tomorrow's globalised society. Adult TCKs (ATCKs) in particular are thought to be more cross-culturally competent and open to experience because of their early childhood experiences.