block party or street party is a crowded party in which many members of a single community congregate, either to observe an event of some importance or simply for mutual enjoyment.

The name comes from the form of the party, which often involves closing an entire city block to vehicle traffic. Many times, there will be a celebration in the form of playing music and dance and activities like pony rides, inflatable slides, popcorn machines and barbecues.

As a form of activism street parties are festive and/or artistic efforts to reclaim roadways as public space by large groups of people. They were made known in Western Europe and North America by the actions of Reclaim the Streets , a widespread «dis-organization» dedicated to reclaiming public space from automobiles and consumerism.