Child marriage is a practice in which the parents of a small child (even infants) arrange a future marriage with another child's parents. The children are betrothed or promised to each other. Often the two children never even meet each other until the wedding ceremony, when they are both of an acceptable marriageable age -- which age differs based upon custom. In some cultures, the age is at or even before the onset of puberty.

Child marriage has been practiced in many cultures for centuries. It continues to this day, although it has extremely few advocates. The practice has been popular in India and Sub-Saharan Africa. It was also common among the nobility of some countries, with betrothal being used to secure political alliances in much the same way that marriage was.

The rationale behind this practice is that a child's parents can arrange a sensible match with the parents of a child from a suitable family, thus securing the child's future at a young age. Many people who have been married in this way do grow to love and cherish their spouses after the marriage. It is thought by adherents that romantic love is not a suitable foundation upon which to build a marriage and a family.

Families are able to cement political and/or financial ties by having children intermarry. The betrothal is considered a binding contract upon the families and the children. The breaking of a betrothal can have serious consequences for both the families and the children themselves. The practice of child marriage has continued to fall further and further out of favor in modern times; however, it is still practiced by some sub-cultures.