Gallagher graduated from Tufts University, where he was active in theater, appearing in such shows as Stephen Sondheim's Company and singing with the all-male a cappella group the Beelzebubs.
Gallagher lulus dari Tufts University, di mana ia telah aktif dalam teater, tampil di acara seperti Stephen Sondheim's Company dan bernyanyi dengan semua laki-laki a cappella kelompok Beelzebubs.