Abstract: Disclosed is a new mixing device for joint compound and the like for mixing pre-blended and newly blended viscous liquid compounds within a cylindrical flat-bottomed container to obtain homogeneous consistency of the compound. The mixing device for joint compound and the like comprises a paddle member adapted to be rotatively driven by a conventional drill motor. The paddle member comprises a unitarily formed, essentially rigid rod having an elongated vertical shank portion with a collinearly formed chuck engagable portion on the proximal end thereof. An agitator blade portion is formed on the distal end of the shank portion. The agitator blade portion includes vertical and horizontal rod portions for efficient mixing of compound near the container sides and bottom. Angled rod portions are also included for efficient mixing of compound in the central area of the container.