Plant endophytes, or bacteria and fungi that occur within plant tissues, comprise a cryptic component of plant communities and yet are critical drivers of plant performance, trophic interactions, and entire plant community dynamics. Indeed, global studies of endophytes have increased exponentially in recent years, and the advent of sequencing technologies have allowed scientists to ask more sophisticated questions about these microbes. Our first goal was to review and synthesize the studies to date on plant endophyte diversity and distributions globally. Specifically, among 596 published studies, we found that high-throughput sequencing studies of fungal and bacterial endophyte studies were vastly underrepresented (26%) compared to culture-based studies (74%), and that studies among temperate grasslands were understudied compared to tropical and temperate forests (>50%). Moreover, almost all studies were purely observational, with little understanding of the drivers and impacts of endophyte communities on plant hosts. We used our findings to develop a new long-term research project on the distributions and impacts of plant microbiomes among grassland communities at the Rio Mora National Wildlife Refuge in northern New Mexico. Specifically, we are testing the degree to which endophytes impact plant communities among management regimes using commercial fungicides, bison exclosures, and prescribed fires. Our study will be the first to empirically test the importance of plant endophytes in mediating important interactions and services, and may ultimately contribute to the management and restoration of grassland ecosystems.