4 pp. / Summer cover crops can add nitrogen to the soil, build up and maintain soil organic matter, suppress pest populations, mitigate soil erosion, and reduce nutrient leaching when they are used in Arizona vegetable systems. However, careful management is required since cover crops can modify the availability of soil nitrogen and other critical nutrients. The ratio between carbon to nitrogen (C:N) in decomposing cover crop biomass is a critical indicator of the overall process of breakdown and eventual release of nutrients. This article introduces five cover crops that could improve vegetable systems in Arizona. The mixtures of a legume and a non-legume cover crop species can also be planted to obtain desired C:N ratios to optimize the benefits of cover crops.