A rooming house, also called a "multi-tenant house", is a "dwelling with multiple rooms rented out individually", in which the tenants share kitchen and often bathroom facilities. Rooming houses are often used as housing for low-income people, as rooming houses (along with single room occupancy units in hotels) are the least expensive housing for single adults. Rooming houses are usually owned and operated by private landlords. Rooming houses are better described as a "living arrangement" rather than a specially "built form" of housing; rooming houses involve people who are not related living together, often in an existing house, and sharing a kitchen, bathroom (in most cases), and a living room or dining room. Rooming houses in this way are similar to group homes and other roommate situations. While there are purpose-built rooming houses, these are rare.

A study of rooming houses in Ottawa, Ontario, in 2016 found that "many units are in very poor condition", with issues such as mould, cockroaches, bedbugs, and broken locks. An article about Montreal rooming houses stated that the units often contain bedbugs and "faulty plumbing".

Rooming houses tend to be located in places close to access, amenities and markets. Specialist builders tend to build up to nine high-standard, low-maintenance micro apartments where once a single occupancy dwelling would have returned just one rental.

In one Ottawa study, more than 50% of the occupants in rooming houses were found to have mental health diagnoses. A 1998 study of Toronto rooming house residents found that they had poorer health than the general population and low incomes.

A study of 295 residents from 171 rooming houses in Toronto found that "residents aged 35 years and older had significantly poorer health status than their counterparts in the Canadian general population" and the residents had a "high prevalence of ill health", with the worst-off residents (from a health perspective) living in the poorest-maintained and most substandard rooming houses.

An article about rooming houses in Montreal stated that rooming houses are the "last stop before the street" for low-income people at risk of homelessness.

Not all rooming houses are legal, inspected units, as some landlords also rent out unlicensed rooms. In Winnipeg, four branches of city government regulate rooming houses: a licensing branch, a business branch, a "livability" living standards bylaw and the fire prevention branch. The livability standards bylaw requires at least one bathroom for 10 residents (some health researchers have called for one bathroom for every four tenants).

Despite efforts by the city of Toronto to regulate rooming houses, there is an invisible, unregistered rooming house sector, which are advertised online or on bulletin boards, often in suburban basements which are subdivided into rooms. Increasing regulation of rooming houses can lead to a decline in the number of rooming houses that are available, as landlords may choose not to apply for and pay the fees for a city licence, and complete the needed safety requirements (sprinklers, fire escapes, etc.).