We report the improvement of glass-forming ability by using Nd to substitute Y in the Mg–Cu–Y bulk metallic glass (BMG). A search in the Mg–Cu–(Y, Nd) pseudo-ternary system located the best glass former at the Mg 57 Cu 31 Y 6.6 Nd 5.4 composition, where the critical size for BMG formation (diameter D c for copper mold casting) reached at least 14 mm. In comparison with the ternary Mg–Cu–Y glass, the Nd-containing BMG, without a significant change in Poisson's ratio, exhibits higher strength and improved compressive plasticity.