The study of behavioral neuroendocrinology encompasses a number of evolutionarily important behaviors regulated by a variety of hormones that act on receptors throughout the brain via diverse mechanisms to modulate development and behavior.  Hormone-brain interactions regulate a wide range of biological processes such as fetal development, puberty, stress, arousal, appetite, and gene expression. The numerous hormone types, including estrogens, androgens, gonadotropins, leptin, corticosterone, oxytocin, vasopressin, insulin, glucagon, epinephrine, norepinephrine, somatostatin, and thyroid hormone, in conjunction with several classes of receptors and brain area targets make this field of study both complex and important. Hormones also play an essential role in sex-specific behaviors and responses, and evaluation of hormonal status and neuroendocrine interactions are important in the consideration of sex as a biological variable, which is a significant issue that is gaining acknowledgment. In addition, hormones regulate immune response and the HPA axis, and hormonal dysregulation is implicated in mood, metabolic, and sexual disorders, making neuroendocrine pathways important drug targets. This collection brings together an array of behavioral and procedural methods that aid in our understanding of highly conserved behaviors and developmental processes that are critical for survival and reproductive success and dependent on hormone mechanisms in the brain. Topics may include parental behavior, social affiliative behavior, aggression, and reproductive behavior.