This chapter reviews in detail the dynamics of anastomosing and anabranching river systems. The difference between anastomosing and anabranching rivers as well as the difference between anastomosing/anabranching and braided rivers is outlined in detail. Anastomosing rivers are examined as a distinctive form of low-energy fluvial systems and of the world’s largest rivers. Anabranching is introduced as a generic type of multichannel river form of which anastomosing is a distinct subcategory. Mechanisms of avulsion, the key process associated with dynamic change of anabranching rivers, are reviewed. The dynamics of wandering gravel-bed rivers, a distinctive type of anabranching river, are explored along with examples of other types of anabranching systems, including those in dryland environments.