Organic petrographic and organic geochemical studies have been conducted on 58 sediment samples of differing ages and depositional environments. In this study, interpretations of petroleum source-rock potential, based on data from transmitted-light microscopy, show a poor correlation with those derived from chemical data. This lack of correlation arises from the failure to distinguish consistently between hydrogen-poor and hydrogen-rich amorphous organic matter and inability to detect hydrogen-rich components (exinite and resinite) in coal fragments. Interpretations based on data from reflected-light microscopy show a better correlation with those derived from chemical studies, but difficulties still remain. These difficulties arise from inability, except on the basis of luorescence intensity, to distinguish hydrogen-rich from hydrogen-poor organic matter in a finely dispersed state.