Layered trigonal EuMg2Bi2 is reported to be a topological semimetal that hosts multiple Dirac points that may be gapped or split by the onset of magnetic order. Here, we report zero-field single-crystal neutron-diffraction and bulk magnetic susceptibility measurements versus temperature χ(T) of EuMg2Bi2 that show the intraplane ordering is ferromagnetic (Eu2+,S=7/2) with the moments aligned in the ab plane while adjacent layers are aligned antiferromagnetically (i.e., A-type antiferromagnetism) below the Néel temperature.