\magnification=1440 \font\bigtenrm=cmr10 scaled\magstep4 Abstract for Michael Hirschhorn and James A. Sellers, Two Congruences Involving 4-cores The goal of this paper is to prove two new congruences involving 4--cores using elementary techniques; namely, if $a_4(n)$ denotes the number of 4--cores of $n$, then $a_4(9n+2)\equiv 0$ (mod 2) and $a_4(9n+8)\equiv 0$ (mod 4). \bye .