Annelida is a diverse group of animals, commonly referred to as segmented worms and currently comprising around 14000 described species. Found in most marine and freshwater areas, annelids have also successfully occupied many subterranean habitats. This volume documents annelid reproduction in the context of their phylogenetic relationships. It presents an introduction and overview to the current systematics of annelids and provides reviews to broad aspects of reproduction across Annelida. The chapters cover oogenesis, sperm, mating, early development, larval development and larval ecology. The book also covers some of the major clades (or purported clades) of annelids and addresses similar issues. The final chapter covers some of the more problematic annelid groups in terms of their phylogenetic placement.