The expansion of urban areas is occurring globally, but not all city neighborhoods are gaining population. Because of economic decline and the recent foreclosure crisis, many U.S. cities are demolishing abandoned residential structures to create parcels of vacant land. In some cities, weak housing markets have, or will likely, recover in the near term, and these parcels will be redeveloped. However, in other cities, large numbers of abandoned parcels have no significant market value and no likelihood of near-term redevelopment. The creation of these vacated green spaces could offer opportunities to preserve declining species, restore ecosystem functions, and support diverse ecosystem services. Arthropods are an important indicator of the ability of urban vacant land to serve multiple functions, from conservation to food production. Across Europe, vacant lands have been found to support a diversity of rare species, and similar examinations of arthropods within this habitat are underway in the United States. In addition, using vacant land as a resource for local food production is growing rapidly worldwide. Arthropods play key roles in the sustainability of food production in cities, and land conversion to farming has been found to influence their community composition and function. A greater focus on quantifying the current ecological value of vacant land and further assessment of how changes in its ecosystem management affect biodiversity and ecosystem processes is clearly needed. Herein, we specifically focus on the role of arthropods in addressing these priorities to advance our ecological understanding of the functional role of vacant land habitats in cities.