Drain clean-out assemblies that can be used to drain the contents of a drain line prior to removing a clean-out plug mounted to the assembly or to which the assembly is mounted. The drain clean-out assembly includes clean-out plug and a device for selectively preventing and permitting drainage of a fluid through a drain port of the assembly. The assembly may include a housing having oppositely-disposed first and second ends, wherein the first end of the housing is configured to attach to a drain line, the second end of the housing is a clean-out port, the clean-out plug is removably attached to the clean-out port, and the drain port is defined by and through the clean-out plug and in fluidic communication with an interior of the housing.