A direct nondestructive method for source-rock evaluation based on solid-state nuclear magnetic resonance (NMR) techniques is demonstrated. Direct measurement of the aliphatic and aromatic carbon structures of the total organic matter in whole rocks is provided by NMR techniques known as cross polarization with magic-angle spinning. The proportion of organic carbon present in aliphatic structures correlates with the oil-generating potential of a source rock. In addition, whether the organic matter in the rock has been altered during catagenesis can be evaluated. These evaluations are demonstrated for carbonaceous shales from the Retort and Meade Peak Phosphatic Shale Members of the Permian Phosphoria Formation. The NMR results show that the Retort shales have a high poten ial to generate oil, but the Meade Peak shales, having already undergone thermal alteration, have a low potential to generate additional oil.