We report the results of a comprehensive study of the mechanical properties and chemical structure of carbon nitride thin films deposited by magnetron sputtering. Nanoindentation measurements show that the films an very elastic. Using a modified Oliver-Pharr method, to account for the elasticity of the films, the reduced elastic modulus was calculated to fall in the range of 35-55 OPa for all films measured. No quantifiable plastic deformation was measured in the tested films, therefore the hardness calculated (6 GPa) can only be assumed to be a lower bound. Fourier transform infrared spectroscopy of the carbon nitride films indicates the presence of large amounts of single and double bonds, and very small amounts of triple bonding, between carbon and nitrogen. Near edge x-ray absorption fine structure data suggests that there are three predominant types of bonds between carbon and nitrogen. This is consistent with the x-ray photoelectron spectroscopy data which shows N(ls) and C(ls) core spectra with multiple, chemically shifted features, The data suggest, but do not confirm, the presence of nitrogen atoms participating in four bonds (three sigma, one pi). A self-consistent argument is presented that links parametric changes in mechanical properties with changes in a proposed film structure based on nitrogen participating in four bonds. This marks a new approach to the interpretation of nitrogen bonding with carbon in the solid state not only for amorphous carbon nitride, but also other systems such as diamond and boron nitride thin films.