Although historically the fields of organic and inorganic chemistry have generally been studied separately, these classes of compound coexist ubiquitously throughout geologic environments. Increasingly, Earth and environmental scientists are recognizing the importance of organic-inorganic interactions in a wide variety of geochemical processes. However, the study of these interactions requires the development of new paradigms for understanding how these complex systems function. For example, traditional models for the formation of oil and natural gas typically involve a catagenic process dominated by thermal cracking reactions that release low-molecular-mass hydrocarbon fragments. These reactions are viewed as unidirectional, kinetically controlled processes that are influenced solely by time, temperature and the composition and structural characteristics of the source kerogen. However, inorganic compounds such as water and minerals may participate as reactants or catalysts during organic matter maturation. Moreover, many organic alteration products participate in processes that create or destroy sediment porosity and permeability, which has direct implications for petroleum migration and trapping. Other examples of important organic-inorganic interactions include: aqueous-organic redox reactions, mineral catalysis of petroleum generation, mineral absorption of hydrocarbons, thermochemical sulfate reduction, organic acid formation, catalysis of natural gas formation, water and minerals as sources of reactive H and O, and the effect of hydrocarbon oxidation on carbonate systematics.