The study of streams and rivers combines ecology, chemistry, hydrology, and geology to reveal factors that control the biological diversity and functioning of these unique ecosystems. Although stream ecology is a relatively young discipline, foundational papers published over the past half-century have shaped our current understanding of these ecosystems and have informed our efforts to manage and protect them. Organized thematically, each chapter of this book–on topics including the physical template, communities, food webs, ecosystem energetics, and nutrient dynamics–offers summaries of the key literature, history and context on the topic, and forward-looking discussions that examine how past research has influenced current studies and may shape future efforts.