Abstract: The phyllosphere comprises the aerial parts of plants and is dominated by the leaves. Microbes that colonize the aerial habitat are termed phyllosphere microorganisms, and form a complex ecosystem within the environment. Conventional culture-dependent methodologies have provided partial information, but are limited by the medium and culture conditions. Recently, a significant advance in molecular biology and informatics techniques revealed vital clues regarding information on the identities and properties of microbial groups in the phyllosphere. Complex interactions are expected to occur in the phyllosphere between various microorganisms as well as between microorganisms and host plants. This article reviews the latest research on the diversity and multipartite interactions in phyllosphere bacterial communities, providing new insight into the relationships between phyllosphere microorganisms and contributing to more effective, less environmentally damaging means of plant pest control.