Cover crops were initially used to improve the soil, prevent erosion and manage nutrients, but they can also be used to alleviate soil compaction, manage pests, attract pollinators and more broadly, increase plant biodiversity in otherwise less diverse monoculture or biculture systems (e.g. corn/soybean). This chapter focuses on cover crop effects on biodiversity of—the arthropods—which play pivotal roles in food webs, nutrient cycling, plant production, and pollination. Numerous studies indicate that cover crops can increase arthropod abundance and biodiversity, although effects are not always consistent and can depend on a variety of factors. This paper shows that an improved understanding of which cover crop species and management approaches optimize biodiversity will make a great contribution to improving the sustainability of agricultural systems.