A bachelorette party or hen night is a party held for a woman who will soon be married. While Beth Montemurro concludes that the bachelorette party is modelled after the centuries-old stag night in the US, which is itself historically a dinner given by the bridegroom to his friends shortly before his wedding, Sheila Young argues that its British counterpart evolved from a number of earlier pre-wedding traditions for women whose origins are obscure but which have been around for at least a century in factories and offices across the UK. Despite its reputation as "a sodden farewell to maiden days" or "an evening of debauchery", these events can simply be parties given in honor of the bride-to-be, in the style that is common to that social circle.

A bachelor party, also known as a stag weekend, stag do or stag party, or a buck's night, is a party held/arranged by the man who is shortly to enter marriage.