To any four-dimensional N=2 super-conformal field theory (SCFT) one can canonically associate a two-dimensional vertex operator algebra (VOA). This provides a powerful framework for the analysis of SCFTs and leads to surprising predictions for a large new class of VOAs. In this talk I will present remarkable free field realizations of the relevant VOAs which mirror the effective field theory description of the corresponding four dimensional theory on the Higgs branch of its moduli space of vacua.