We calculate the plasmon mass in classical real time Yang-Mills theory on the lattice. We study both an isotropic 3-dimensional
case and an extremely anistropic 2-dimensional system. We use three methods to determine the plasmon mass: a hard thermal loop
expression in terms of the particle distribution, an effective dispersion relation, and by measuring oscillations between
electric and magnetic field modes after artificially introducing a homogeneous E-field. We find that these methods agree better
in the very anisotropic case.