The phyllosphere microbiome consists of the genetic content of the microorganisms that colonize the external aerial portions of plants. Relationships of plant responses to specific microorganisms--both pathogenic and beneficial--have been examined, but responses of the phyllosphere microbiome overall are not well described. Changing crop growth conditions such as increased drought can have profound impacts on crop productivity and epiphytic microbial communities provide a new target for crop yield optimization. We provide the first comparison of Zea mays leaf microbiomes between drought and well-watered conditions. We examined the maize leaf phyllosphere microbiome from three physically disparate locations with and without drought treatment, through the application of deep sequencing with short sequence read technology. Functional profiles revealed a wide variety of metabolic and regulatory processes including the ability to adapt to changing environmental conditions associated with, and external to the plant and the presence of potential plant growth promoting traits suggesting possible beneficial plant-microbiome interactions. Both specific field site and drought affected taxonomic and functional composition of these leaf epiphyte communities.