The biogeochemistry of sulfur is of widespread interest in the earth science community due to its impact on many different biogeochemical processes. Organic sulfur is of particular interest due to its impact on petroleum formation and refining and its relationship to microbial sedimentary processes, organic carbon accumulation, and the overall integrity of paleoenvironmental proxy records. This paper reviews many of the advances in organic sulfur biogeochemical research spanning the past ∼15 years. These advances include (1) an improved mechanistic understanding of why sulfur-rich organic deposits form petroleum products earlier during diagenesis than sulfur-poor deposits, (2) constraints on the timing and pathways of organic sulfur formation as well as the forms of organic sulfur present in the environment, and (3) recognition of the impacts of organic matter sulfurization on organic carbon preservation at bulk and molecular scales and the implications of this enhanced preservation for paleoenvironmental studies.