Act your age

Meaning

Behave at a maturity level expected for your age.

Usage

Used when someone is acting too immature or irresponsible.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

Etiquette guidance telling people to match behavior with age.

Appears in 20th-century parenting and schooling advice.