The goal of this research was the fabrication of thin films with magneto-optic (MO) properties. Accomplishment of this task was achieved via sol-gel processing of rare-earth and aluminum substituted yttrium-iron garnet (RxY3-xAlyFe5-yO12, R,Al:YIG), where R= Bi, Gd, Er, Ho. Detailed are the processing conditions, parameters and results leading to R,Al:YIG films with MO response. Success was attained with a 0.25M Gd,Al:YIG solution spin coated for 120 seconds at 3500rpm onto a (111) gadolinium gallium garnet (GGG) substrate and calcinated at 900°C for 4 hours. Samples were characterized via x-ray diffraction (XRD), magneto-optical loop tracer, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), profilometry and optical microscopy. / Master of Science