We study the development of adult body plans by a strong focus on understanding embryonic development. Most animal developmental models are defined by direct development, where the adult body plan forms directly during embryogenesis. However, in many bilaterian phyla, the embryo gives rise to a larval body plan, that is often characterized by a body plan very distinct from the adults that they give rise to. The adult body plan forms postembryonically, often weeks into larval development. Most broad evolutionary body plan comparative studies compare developmental mechanisms of embryos without considering the mode of development of the animals being compared and how this may affect the analysis. In this course we will explore the diversity of developmental strategies in animal phyla and discuss the importance of integrating a more explicit consideration of life history into broad body plan comparisons across distantly related phyla.