The structures of low-alkali-content xNa2S + (1 - x)B 2S3 (x ≤ 0.2) glasses have been studied by neutron and synchrotron X-ray diffraction. Similar results were obtained both in neutron and synchrotron X-ray diffraction experiments. One significant difference, however, is that with the higher resolution obtainable in the X-ray atomic distribution function data, the peak at 1.8 Å splits into two components, one at 1.8 Å and one at 1.93 Å with the addition of Na2S to B2S3. The experimental total atomic distribution functions have been compared to model ones computed on the basis of structure data for crystalline counterparts of the glasses. The results provide direct structural evidence that doping B2S3 with Na2S creates a large fraction of tetrahedrally coordinated borons in the glass.