Recently, wide band gap II-IV-N2 semiconductors such as ZnSiN2, and ZnGeN2 and ZnSiGeN2 have been synthesized, but very little is known about their band structure, optical properties, or electronic properties. Bulk crystals are hard to synthesize because high temperatures and pressures are required. The success in growing II-IV-N2 films epitaxially by MOCVD creates interesting opportunities. The crystal structure of II-IV-N2 compounds is orthorhombic, and when grown on r-plane sapphire can provide a suitable template for GaN growth. Optical transmission studies of the band edge of ZnSiN2 and ZnSiGeN2 with varying Si and Ge percentages were conducted. The indirect nature of the band gap was investigated, and prism coupling was used to obtain the refractive indices in the visible and NIR portion of the spectrum. Although the crystal symmetry was orthorhombic, the refractive indices indicated uniaxial optical properties. Optical loss measurements indicate that the films are suitable for waveguides and novel devices based on birefringent optical effects.