  We show that local moment screening in a Kondo lattice with d-wave
superconducting conduction electrons is qualitatively different from the
corresponding single Kondo impurity case. Despite the conduction-electron
pseudogap, Kondo-lattice screening is stable if the gap amplitude obeys $\Delta
<\sqrt{\tk D}$, in contrast to the single impurity condition $\Delta <\tk$
(where $\tk$ is the Kondo temperature for $\Delta = 0$ and D is the bandwidth).
Our theory explains the heavy electron behavior in the d-wave superconductor
Nd_{2-x}Ce_{x}CuO_{4}.
