Magnetization‐versus‐temperature (M‐vs‐T) measurements in a fixed field on cubic pseudobinary Tb0.3Y0.7Ag show thatMfor increasing and then decreasingTbifurcates at the antiferromagnetic Ne´el point (TN=36 K), whereMis maximum. The resulting thermoremanence (MR), which decays very slowly with time, diminishes with increasingTand vanishes atTN. Thus, the long‐range antiferromagnetism appears to coexist with spin‐glass ordering. Measurements ofMRwith increasingTwere also made for different cooling fields (Hc1) The changes ofMRwithHclandTare found to reduce to a universal relationship between the temperature‐normalized quantities,m=MR/M0(T) andh=Hcl/H0(T). Setting both the initial slope ofmvshand the saturationmat highhequal to unity, we determine thatM0(T)=M0(0) exp (−T/T0), withM0(0)=0.82&mgr;B/Tb atom andT0=4.3 K, and thatH0(T) varies analogously, withH0(0)=225 kOe and the sameT0. A similar temperature scaling ofMRvsHcl, with similar exponential forms forM0(T) andH0(T), has been deduced earlier for Ag‐Mn and other canonical spin glasses.