Abstract: An improved modular breadboard for temporarily mounting and interconnecting electrical components to form an electronic circuit. The breadboard includes two panel assemblies which are mounted on leg brackets to extend parallel and spaced apart. Modules mounting preselected circuit components or circuit subassemblies are releasably locked between the panel assemblies with spring loaded fingers on one or both of the panel assemblies. The modules and the panel assemblies are provided with a plurality of solderless spring terminals and binding posts for temporarily connecting wires and circuit components to form the experimental circuit.