A sacristy, also known as a vestry or preparation room, is a room in Christian churches for the keeping of vestments (such as the alb and chasuble) and other church furnishings, sacred vessels, and parish records.

The sacristy is usually located inside the church, but in some cases it is an annex or separate building (as in some monasteries). In most older churches, a sacristy is near a side altar, or more usually behind or on a side of the main altar.

In newer churches the sacristy is often in another location, such as near the entrances to the church. Some churches have more than one sacristy, each of which will have a specific function. Often additional sacristies are used for maintaining the church and its items, such as candles and other materials.