Systems and devices for emitting volatile materials are disclosed. In some embodiments, devices for emitting two or more fragrance compositions are disclosed. In one non-limiting embodiment of a device, the device has a housing, and the housing is supported on an electrical outlet by a plug at least indirectly joined to the housing. The device contains a first volatile composition and a second volatile composition. The first volatile composition is emitted in an alternating period relative to said second volatile composition. In one embodiment of the device, the volatile compositions are alternately emitted during periods that are each greater than 15 minutes to about 24 hours in length.