Adult behaviors are the result of interactions between an individual’s genes and their developmental environment. Although past research has demonstrated the importance of early-life experiences in later behavior, most work focuses on the impact of a single experience. However, early life is a slew of experiences that can interact with each other, and adult phenotypes may be the result of a suite of interrelated developmental experiences. Here, I explore the potential variation and impact of three interconnected developmental experiences in the prairie vole: parental care, alloparental experience, and exposure to the nonapeptides oxytocin (OT) and arginine vasopressin (AVP) (introduced in Chapter 1). I then characterize the variation present in prairie vole parental care and show that pups prefer to interact with their mothers over fathers, regardless of this variation (Chapter 2). This maternal preference disappears after weaning. Next, I explore the behavioral and neural components of alloparenting in subadult (post-weaning, pre-sexual maturity) prairie voles by exposing them to one of four stimuli: a same-age sibling, a related neonate, an unrelated neonate, or an inanimate object (Chapter 3). Subadult alloparents show no difference in the amount of care they give to related and unrelated neonates and no difference in OT or AVP activation in the paraventricular nucleus of the hypothalamus (PVN) or supraoptic nucleus of the hypothalamus (SON) across stimuli. This suggests that subadult alloparental experience is important practice for their future parenting. I then explore using the Morris water maze how chronic and acute intranasal administration of OT and AVP impact spatial memory in adulthood, a form of cognition underlying monogamous mating tactics (Chapter 4). Only chronic administration of AVP during post-weaning development influences spatial memory, specifically by improving it. Finally, I speculate on ways all three developmental experiences may impact each other and influence adult cognition (Chapter 5). I hypothesize that these early-life experiences can interact with each other to ultimately organize neural phenotype, thereby affecting the adult behavioral phenotype. Experiences during development can cause a cascade of potentially interconnected events that account for the range of adult behaviors linked to early-life variability.