Although buffel grass (Cenchrus ciliaris) invasions on several continents have significant ecological impacts, little information is available on its effect on seedling emergence and establishment of native vegetation. In highly impacted areas of the Sonoran Desert of North America, perennial plants are particularly vulnerable during their seedling stage. We studied the impact of buffel grass on the emergence and early survival of native seedlings in a field experiment. We marked out 2m x 2m field plots at three locations near Tucson, Arizona, with and without buffel grass. We removed the buffel grass from half of those with the invasion, and censused and marked native perennial seedlings that emerged in each plot for ten weeks during July-September (monsoon season) of 2013. Emergence and survival of native perennials in the field were both significantly higher where mature buffel grass was removed or had never invaded than where it remained. Our results highlight the need for more manipulative studies of density to improve mechanistic understanding of population dynamics, and to forecast how populations and communities will respond in the long term to perturbations such as invasion.