Lattice QCD Calculations of Leptonic and Semileptonic Decays

In lattice QCD, obtaining properties of heavy-light mesons has been easier said than done. Focusing on the $B$ meson's decay constant, it is argued that towards the end of 1997 the last obstacles were removed, at least in the quenched approximation. These developments, which resulted from a fuller understanding and implementation of ideas in effective field theory, bode well for current studies of neutral meson mixing and of semileptonic decays.