This is the seventh volume of a ten-volume series on The Natural History of the Crustacea. Chapters in this volume synthesize our current understanding of early crustacean development from the egg through the embryonic and larval phase. The first part of this book focuses on the elemental aspects of crustacean embryonic development. The second part of the book provides an account of the larval phase of crustaceans and describes processes that influence the development from hatching to an adult-like juvenile. The third and final part of the book explores ecological interactions during the planktonic phase and how crustacean larvae manage to find food, navigate the dynamic water column, and avoid predators in a medium that offers few refuges.