The recent announcement of the synthesis of C3N4 has increased interest in this unique material. Carbon nitride may have several useful applications as wear and corrosion resistant coatings, electrical insulators, and optical coatings. We have produced amorphous carbon nitride coatings containing up to 40% nitrogen using planar magnetron RF sputtering with and without an ion beam in a nitrogen atmosphere. Both wavelength dispersive x-ray spectrometry (WDX) and x-ray photoelectron spectroscopy (XPS) indicate this composition. Coatings up to 2 μm thick were produced on alumina, silicon, SiO2, and glass substrates using a graphite target. Films with transparency greater than 95% in the visible wavelengths and harder than silicon have been produced. The properties of these films are correlated with composition, fabrication, conditions, and subsequent heat treatments. A scanning tunneling microscope (STM) and transmission electron microscopy (TEM) were used to characterize the morphology of the films. XPS studies confirm the stability of a carbon nitrogen phase up to 600 °C. Compositional variations were determined with secondary ion mass spectrometry (SIMS) depth profiling, and the Raman spectra are compared with those of carbon and carbon nitride films prepared by other methods.