In Christianity, a church service is a term used to describe a formalized period of worship, often but not exclusively occurring on Sunday, or Saturday in the case of a church practicing Sabbatarianism. The church service and its conduct is seen as being a primary, although not the sole, purpose for the existence of the church.

Styles of service vary greatly, from the Roman Catholic and Eastern Orthodox traditions of liturgical worship to the evangelical Protestant style, which often combines worship with an outreach to non-Christians and/or non-practicing Christians in the audience.