  We report on a comprehensive optical, transport and thermodynamic study of
the Zintl compound Yb$_{14}$MnSb$_{11}$, demonstrating that it is the first
ferromagnetic Kondo lattice compound in the underscreened limit. We propose a
scenerio whereby the combination of Kondo and Jahn-Teller effects provides a
consistent explanation of both transport and optical data.
