<p>The structure of metacommunities has been attributed mainly to local (e.g., abiotic conditions and biotic interactions) and spatial factors (e.g., dispersal limitation and mass effect). However, our knowledge of the relative roles of these factors in structuring metacommunities at large spatial extents is unknown, especially using fine-grained data. Using a large data set from lakes covering the continental United States of America and encompassing phytoplankton, zooplankton, and macroinvertebrate communities, I assessed the relative importance of local environmental factors, climatic, and spatial variables using variance partitioning procedures. The phytoplankton metacommunity exhibited a strong spatial structure, whereas the zooplankton and macroinvertebrates metacommunities were mainly related to spatially structured environmental variables. In general, these results did not align with the expectations that small-bodied communities—with high dispersal ability—would be mainly related to local environmental factors and that relatively large-bodied communities – with low dispersal ability—would be associated primarily with spatial processes.</p>