A variety of pyrolysis systems can be used to obtain source rock evaluation and other data. Systems with bulk flow capabilities are best used to screen samples for subsequent detailed analysis, but data must be interpreted in the light of possible mineral-pyrolysate interactions. Non-indigenous hydrocarbons can be detected by the same techniques, but pyrolysis-FID/-gc or alternatively pyrolysis-gc plus pyrolysis-bulk flow are required to identify and differentiate migrated hydrocarbons and refined petroleum products. Screening can be carried out in the laboratory or at the well location. In the latter case, data can be used for on-site decision making, as well as providing the groundwork for subsequent geochemical studies. Pyrolysis-FID/-gc provides the most comprehensive means for screening in both laboratory and well-site situations. For detailed geochemical analysis, pyrolysis-gc is the most versatile technique, providing both quantitative and qualitative ways to identify kerogen type, classify bitumens, and recognize contamination.