An au pair (plural: au pairs) is a foreign-national domestic assistant working for, and living as part of, a host family. Typically, au pairs take on a share of the family's responsibility for childcare as well as some housework, and receive a small monetary allowance for personal use.

The title comes from the French term au pair, meaning "on a par" or "equal to", indicating that the relationship is intended to be one of equals: the au pair is intended to become a member of the family, albeit a temporary one, rather than a domestic servant. In the best circumstances, both parties benefit from learning about the other's culture and will remain on good terms long after the au pair has left the family.