Abstract: An interlocking display panel assembly comprises a pair of end elements for attachment to a supporting surface, at least one intermediate element having an indicia displaying surface locatable in an interlocking relationship between the end elements to form an integral planar assembly, illumination devices in the intermediate elements. Each element interlocks with an adjacent element by means of a tongue-and-groove arrangement, male and female portions of the tongue-and-groove arrangements on opposite sides of the intermediate elements being arranged in a complementary manner so that as many intermediate elements can be fitted together in a row as desired. Respective contacts are provided on opposing surfaces of adjacent interlocking elements so as to transfer electrical power between adjacent elements. One of the end elements includes a device for providing power to the assembly.