Breaking waves in shallow waters drive mean currents and low-frequency eddies within the surf zone. These rotational flows alter the transport and mixing of contaminants, bacteria, larvae, and other materials within coastal environments. Surf-zone vortices are driven by several mechanisms, including instabilities in mean flows and spatial gradients in wave forcing. This talk describes experimental and numerical investigations into these mechanisms. We first characterize the vorticity injected by individual breaking waves through wave-basin experiments and Boussinesq model simulations. We then quantify the relative roles of surf-zone vorticity-generation mechanisms, including instabilities in the vertically sheared undertow, on tracer dispersion in three-dimensional wave-resolving model simulations.