Volume 2, Biology and Ecology of Parenting, relates parenting to its biological roots and sets parenting in its ecological framework. Some aspects of parenting are influenced by the organic makeup of human beings, and the chapters in Part I, on the Biology of Parenting, examine the evolution of parenting, the psychobiological determinants of parenting in nonhumans, and primate parenting, as well as the genetic, prenatal, neuroendocrinological, and neurobiological bases of human parenting. A deep understanding of what it means to parent also depends on the ecologies in which parenting takes place. Beyond the nuclear family, parents are embedded in, influence, and are themselves affected by larger social systems. The chapters in Part II, on the Ecology of Parenting, examine the ancient and modern histories of parenting as well as epidemiology, neighborhoods, educational attainment, socioeconomic status, culture, and environment to provide an overarching relational developmental contextual systems perspective on parenting.