This invention relates to a rotary, manually adjustable, compact potentiometer suitable for panel mounting and which requires a minimum of behind-panel space. The potentiometer comprises a central mounting assembly including a resistor supporting disc and a manually rotatable hollow knob rotatably mounted around the disc so as to form an enclosed resistor chamber. The central mounting assembly further comprising a flange spaced from the disc, an internal flange in the hollow knob trapped between the disc and the central mounting assembly flange, and an arcuate resistance element mounted in the resistor chamber on the disc. A resilient arm is driven by the knob in the resistor chamber and has a movable contact bearing on the resistance element. Electrical conductors extend through the central mounting assembly to the movable contact and resistance element.