Understanding the mechanisms of community assembly, which are the processes that result in a site containing some species and not others, is a fundamental goal of community ecology and macro ecology. In this talk, I will examine the influence of two assembly processes on tropical vertebrate communities across spatial scales: environmental filtering, which occurs when species are found at the sites to which they are best adapted, and dispersal limitation, which occurs when a species that would be able to persist at a site is absent because individuals of the species were limited in their ability to reach the site. Results suggest that while environmental filtering is an important influence at the continental scale, dispersal limitation is a more important influence on community composition at the regional spatial scale.