When a liquid drop impacts on a pool, the drop will either coalesce into the host liquid, with the creation of a vortex ring below the surface and little splashing above, or will splash, producing a cavity in the host liquid that collapses inward, producing an upward jet of fluid. It is found that there is a critical Weber number, Wec=U(&rgr;D/T)1/2&bartil;8, below which vortex rings are formed and above which a jet is produced for drops falling into the identical fluid. Here,Uis the drop speed at impact,Dis the drop diameter, and &rgr; andTare density and surface tension, respectively. The Weber number criterion is compared with experiments using water and mercury.