Background/Question/Methods Alteration of ecosystem composition by exotic plant invasion is a major component of human-induced global environmental change. In California sage scrub (CSS), increases in anthropogenic disturbances have, in many places, caused permanent shifts in the community composition, from native perennial shrubland to exotic annual grassland. Biological soil crusts (BSCs) are delicate ecological structures occupying CSS and are also adversely affected by anthropogenic disturbances. Disturbances of BSC curtail or eliminate their many ecological services, which may include favorable conditions for native plant germination in species adapted to BSC, and the inhibition of exotic plant germination. Using field and greenhouse experiments, I tested the hypothesis that disturbance of BSC increases emergence of exotic vascular plants and decreases emergence of native vascular plants in coastal CSS. At Whiting Ranch Wilderness Park in southern California, 22 plots were established and emergence of exotic and native plants was compared between disturbed and undisturbed subplots containing BSC. In a complementary greenhouse experiment, seed fate (emerged, not emerged, or missing from wind or granivory) in disturbed BSC cores was compared to seed fate in undisturbed BSC cores for three exotic and three native species. Results/Conclusions In the field, disturbance of BSC significantly increased total exotic plant emergence, particularly for annual grasses, whereas total native emergence was greater in undisturbed BSC. Within disturbed subplots, exotic emergence was significantly greater than native emergence. In undisturbed subplots, total native emergence was greater than exotic emergence. In the greenhouse, seed fates for all species were significantly different between disturbed and undisturbed BSC cores. All exotic species showed greater emergence in disturbed BSC cores. Additionally, a greater percent of seeds were missing in undisturbed BSC cores. Native species showed varied responses, including one native annual that showed the greatest emergence among all species in undisturbed BSC cores. Anecdotally, disturbance of BSC—which to the human eye increases the perceptibility of some seeds against the soil surface—seemed to influence granivory by common CSS granivores, specifically birds. Overall, disturbance of BSC in coastal CSS will increase emergence of exotic vascular plants comprised of predominantly annual grasses of Mediterranean origin, modifying community composition and structure. As CSS is located within a biological hotspot, land managers should include BSC as a critical ecological factor affecting exotic plant invasions and therefore ecosystem function.