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Rangeland managers are increasingly prioritizing ecological functions of soil. Soil organic carbon is central to these efforts because it plays a fundamental role in soil fertility, soil stabilization, and water holding capacity. On grazing lands, influencing soil organic carbon via vegetation management is one strategy through which managers may be able to affect change. �For example, promoting deep-rooted perennial grasses is hypothesized to increase soil carbon. However, dynamics between soil organic carbon and the vegetation community are complex, and there is a need to understand broad patterns in soil organic carbon concentrations in relation to plant community composition. In 2016, we surveyed the herbaceous plant community and soil organic carbon at 220 locations in 15 counties in California. Using multiple regression on distance matrices, we found a significant relationship between vegetation community composition and percent soil organic carbon while controlling for geographic location, average annual precipitation, and soil texture. Using indicator species analysis, we found that plant species associated with high soil carbon included several functional groups, including perennial grasses, and plant species associated with low soil carbon were primarily annual forbs. This survey of plant community composition and soil organic carbon provides context for setting management objectives and generating mechanistic hypotheses about plant-soil interactions.