A wall-mountable wireless control device may include an antenna (e.g., a slot antenna or a hybrid slot-patch antenna) for transmitting and/or receiving radio-frequency signals, and may have a conductive material on a large amount (e.g., greater than or equal to approximately 85%) of a front surface of the control device. The wireless control device may operate consistently when installed with different types of faceplate assemblies (e.g., faceplate assemblies having metal and/or plastic components) and when installed with different types of electrical wallboxes (e.g., metal and plastic wallboxes). A faceplate comprising a conductive element may be installed on the wireless control device, such that the conductive element operates as a radiating element of the antenna. The wireless control device may comprise a conductive member (e.g., a conductive label or a conductive strap) extending around a rear enclosure of the wireless control device between opposite sides of a conductive yoke.