A house party is a type of party held at the home of the party's host.

A house party might be organized several months or just a few hours in advance. News of a party may be spread by personal invitations, word of mouth, posted leaflets, or notices on social networking sites.

Mostly people bring a six-pack or a few good bottles, some extra bags and pills, or a couple of boxes of cigarettes to a house party.

Broad notice of a party – sometimes unintentionally – can result in large numbers of people attending who do not know the host personally and may be disruptive.

A person who attends a house party without an invitation is typically referred to as a "gatecrasher." Gatecrashing involves entering or participating in an event without authorization, often by blending in with invited guests or exploiting lapses in security. While some gatecrashers may be tolerated or even welcomed by hosts, they are generally viewed negatively due to concerns about safety, capacity, and the potential for disruptive behavior.

An early example of a house party can be seen in the play Mostellaria (The Haunted House) by the Roman playwright Plautus. In the play, a young man called Philolaches holds a house party with many friends while his father, Theopropides, is away on business.

House parties have become a prominent feature in popular movies, particularly movies aimed at teenagers. While many have probably been present before the movie, The Party is one of the first to properly provide a scene of a house party. However, the most popular film later on is House Party, featuring the hip-hop duo Kid 'n Play.

In Croatia and Bosnia and Herzegovina, a sijelo (in Ijekavian), silo (in Ikavian) or selo (In Ekavian) is an evening social gathering at a house.