When a zoning ordinance is adopted, most states' zoning enabling laws require that a board of zoning appeals or adjustment be created. The board functions as a safety valve through which land owners can seek relief from strict application of a zoning ordinance.

In addition, the board functions to give assurance that zoning procedures are applied fairly, are interpreted properly by staff, and do not cause or produce excessive hardships on property owners. In communities in some states, a single board exercises the responsibilities of both the planning commission and zoning board.