Forest ecosystems are constantly changing due to many factors that are typically described by shifts in species composition, successional stage, or phylogenetic diversity. Recent advancements in remote sensing have revealed the importance of stand structure on forest dynamics. However, the limited availability of LiDAR data prevents the analysis of forest structure across the United States. In this analysis, we compiled data from the U.S. Forest Inventory and Analysis (FIA) Program from 120,000+ plots. We computed metrics related to tree size classes, species diversity, and phylogenetic diversity. We subsetted our data by ecoregion and found a positive relationship between forest structural diversity and both species and phylogenetic diversity at lower levels of structural diversity, but they tend to flatten out or become negative as structural diversity increases. These relationships also vary in strength between ecoregions, which may be related to regional species variability. Moving forward, we will explore the relationship between forest structure and ecosystem functions, which will help broaden our understanding of forest structural dynamics in a changing global environment.