A convenient picture of the ZnGeN2 lattice can be realized by replacement of the Ga atoms in the GaN lattice by alternating Zn and Ge atoms. This replacement results in a 2x2x1 orthorhombic lattice accompanied by a slight distortion of cell shape, and bond angles, and a bimodal distribution of bond lengths.1 GaN and ZnGeN2 have nearly identical lattice constants2 of the underlying wurtzite lattice, and nearly identical band gaps.3 However, we find that the Raman spectra for the two materials are substantially different. The period doubling in two directions in the c-plane compared to the wurtzite lattice results in 78 phonon modes for ZnGeN2, all of them Raman active,4 versus 6 Raman-active modes for GaN. Here, we present polarized Raman spectra on individual, oriented single crystal ZnGeN2 for several scattering geometries. The crystallites, grown by a vapor-liquid-solid method using NH3 and elemental Zn and Ge, are single crystal rods, as determined by electron diffraction, of lengths of the order of 100 μm and approximately hexagonal cross sections of up to 6 μm in width. A comparison of our results with a previously published unpolarized micro-Raman spectrum for polycrystalline material reveals major differences2. These include our observation of many individually resolved Raman peaks, and the absence of spectral weight for frequencies above 850 cm-1. The previously published spectrum shows a strong Raman signal in the entire region from 850-1300 cm-1. This portion of the spectrum, which, again, is absent in our spectrum, has been attributed tentatively to second harmonic overtones of the single phonon spectrum.4 A comparison with theory, including a discussion of the relevant selection rules for different scattering geometries, will be presented.This work was supported partially by grants from the Department of Education ( APR P200A030186), the National Science Foundation (DMR-0420765) and the Air Force Office of Scientific Research (F49620-03-1-0010).1 S. Limpijumnong, S.N. Rashkeev and W.R.L. Lambrecht, MRS Internet J. Nitride Semicond. Res. 4S1, G6.11 (1999).2 R. Viennois, T, Taliercio, V. Potin, A. Errebbahi, B. Gil, S. Charar, A. Haidoux, and J.-C. Tédenac, Mat. Sci. Eng. B82, 45 (2001).3 K. Du, C. Bekele, C.C. Hayman, J.C. Angus, P. Pirouz, and K. Kash, “Synthesis and Characterization of ZnGeN2 grown from Elemental Zn and Ge Sources”, submitted to J. Crystal Growth.4 Walter R.L. Lambrecht, Erik Alldredge and Kwiseon Kim, Phys. Rev. B72, 155202 (2005).