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In the mid-1930s, scientists were attempting to unravel the mechanisms responsible for microbial methane production. Following in the mid-1950s, scientists began assigning a microbial origin to volatile hydrocarbon gas other than methane. Since these earliest reports, biogenic methane and other volatile hydrocarbons have been measured in terrestrial, marine and lacustrine environments. Decades of research have demonstrated that these processes are complex, involving multiple organisms and a plethora of enzymatic processes. However, when combined in the appropriate context, these microbial processes highlight the exciting, important, and unique biogeochemical niche these organisms fill. This review attempts to integrate the microbial and geochemical conditions promoting microbial production of volatile hydrocarbons. As continued research focuses on understanding the environmental and biological limits of biogenic gas production, it appears that these communities have the ability to adapt and survive in the most energy-limited conditions on Earth. The dominant regions of microbial volatile hydrocarbon production are usually restricted to zones with specific geochemical conditions. Biogenic methane production is almost exclusively found in environments where sulfate is depleted and adequate substrates for methanogenesis are available. Conditions leading to the formation of other short-chain volatile hydrocarbons are less well understood. Biogenic methane production requires a hierarchal transfer of energy and substrates among a variety of organisms culminating in terminal carbon remineralization by methanogenic archaea. Recently, the recognition of other microbially produced non-methane hydrocarbons - specifically ethane, propane, and isoprene -has demonstrated the importance of these compounds in many environments. While the mechanisms for the formation of these non-CH4 hydrocarbons are not as well understood as their C1 counterpart, there are likely similarities in the metabolic and geochemical conditions. At the conclusion of this mini-review, a series of basic questions and needs regarding future research objectives regarding the microbial production of methane and non-methane hydrocarbons are proposed, including developing a more comprehensive understanding of the mechanisms leading to their formation and degradation. [ABSTRACT FROM AUTHOR]