The effective magnetic thickness of Fe films and of Fe/Al and Fe/Pd bilayers is determined using Brillouin light scattering. The magnetic thickness is extracted by fitting the field dependence of the frequencies of two magnon modes. Within experimental errors of about 1 Angstrom, no change in the effective magnetic thickness of the Fe layers was detected. If a net magnetization does exist in Pd when in contact with Fe, it is sufficiently different in nature so as to not modify the Fe spin waves.