This review synthesizes patterns in biomass and taxonomic structure of stream benthic algae based on our more recent understandings. Temporal and spatial dimensions are addressed separately, although the two are partly interlinked in determining pattern. This review also considers a range of scales, from patterns occurring on individual substrata over periods of weeks, to patterns over periods of years that can be evident across continents. This synthesis will assist with understanding local, regional, and broadscale community structure and dynamics. It will also provide a conceptual framework for the placement of later chapters in this book, which provide more detailed reviews of specific processes.