A vivarium (Latin, literally for "place of life"; plural: vivaria or vivariums) is an area, usually enclosed, for keeping and raising animals or plants for observation or research. Often, a portion of the ecosystem for a particular species is simulated on a smaller scale, with controls for environmental conditions.

A vivarium may be small enough to sit on a desk or table, such as a terrarium or an aquarium, or may be a very large structure, possibly outdoors. Large vivaria, particularly those holding organisms capable of flight, typically include some sort of a dual-door mechanism such as a sally port for entry and exit, so that the outer door can be closed to prevent escape before the inner door is opened.

There are various forms of vivarium, including:

A vivarium is usually made from clear container (often plastic or glass). Unless it is an aquarium, it does not need to withstand the pressure of water, so it can also be made out of wood or metal, with at least one transparent side. Modern vivariums are sometimes constructed from epoxy-coated plywood and fitted with sliding glass doors. Coating the inside of a plywood vivarium helps to retain the natural effect of the environment. Epoxy-coated plywood vivariums retain heat better than glass or plastic enclosures and are able to withstand high degrees of humidity. They may be cubical, spherical, cuboidal, or other shapes. The choice of materials depends on the desired size and weight of the entire ensemble, resistance to high humidity, the cost and the desired quality.