The sintering of alumina doped with magnesia-based additives to translucency previously has been possible only in atmospheres of hydrogen or oxygen or under vacuum. This paper reports on the sintering of alumina in N-2-H-2 atmospheres that contain as little as 2% H-2, where optical transparency that is equivalent to that of normal H-2 sintering is achieved. In an effort to explain these results, experiments that vary the content of H-2 and H2O, as well as the changes in the dynamic atmosphere, have been conducted. The evidence indicates that the final-stage sintering involves a point-defect pair mechanism that includes hydrogen interstitials and nitrogen solutes.