Community structure of stream benthic macroinvertebrate communities is dictated by a combination of factors that includes habitat filtering, habitat size, the dispersal of organisms within a stream network, and simple stochasticity. However, our perception of these factors is often complicated by seasonal cycles that include dramatic changes in temperature, stream flow, and the various life histories of the organisms of interest. We conducted a year-long study of benthic invertebrates in a river network in western Virginia, USA. Our purpose was to examine not only macroinvertebrates residing in the benthos, but also their two primary dispersal pathways—drifting and aerial dispersal—with the goal of explaining macroinvertebrate patterns within a network. When considering these patterns, we considered three major sources of variation: 1) spatial factors, i.e., location within a river network, 2) temporal factors, i.e., seasonal changes, and 3) environmental conditions. We found that temporal factors and associated seasonal changes in environmental conditions were the primary drivers of macroinvertebrate drift dispersal, regardless of position within a river network. Perhaps most surprisingly, we found very little connection between the communities represented by benthic samples and the paired drift samples from the same sites. These comparisons showed weak correspondence in both composition and total abundance relationships between drifting and benthic communities. These weak correspondences at the community level suggest that drift is largely density-independent and is driven primarily by seasonality and flow regime. These results seem to contradict a number of prior studies suggesting a density-dependent component of drift. However, we reconcile these views based on current theory in community ecology centered around the ideas of connectivity in river networks and how community size changes across river networks.